





^m 



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CHEMISTRY, 



FOR SCHOOLS, FAMILIES, AND PRIVATE STUDENTS. 



BY A. H. LINCOLN PHELPS. 



PRINCIPAL OF THE PATAPSCO FEMALE INSTITUTE, MARYLAND. 



AUTHOR OF THE FIRESIDE FRIEND &C. WITH A SERIES OF WORKS ON BOTANY, NATURAL PHI- 
LOSOPHY AND CHEMISTRY, DESIGNED FOR BEGINNERS AND MORE ADVANCED STUDENTS. 




NEW EDITION, REVISED AND CORRECTED. 



NEW YORK: 
PUBLISHED BY HUNTINGTON AND SAVAGE, 

-~ 216 PEARL STREET. 



.Vs.^ 



Entered according to Act of Congress, in the year 1H46, by 

HUNTINGTON AND SAVAGE, 

In the Clerk's Office of the District Court of the United States for the 

Southern District of New-York. 






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V \. .... 



CONTENTS. 



CHAPTER 



Introductory. General views of Physical Science. Applications of 

Chemistry,... 7 



PART I. 



CHAPTER II. General Remarks on the Imponderables. Heat. Expansion. Ther- 
mometers 13 

" III. Conduction of Heat. Radiation and Reflection. Latent Heat. Li- 
quefaction. Frigorific Mixtures 24 

" IV. Vaporization. Ebullition. Steam. Distillation. Gases and Va- 
pors 36 

w V. Light. Decomposition of Light. Illuminating, Heating, Coloring, 

and Magnetic Rays. Flame. Phosphorescence • 48 

" VI. Galvanism, or Voltaic Electricity 64 

" VII. Chemical Nomenclature 70 

" Vm. Chemical Affinity 77 

PART II. 

CHAPTER IX. Chemical Classifications. Division of Ponderables. Oxygen 93 

" X. Chlorine 100 

" XI. Electro-negative Substances. Bromine. Iodine. Fluorine 105 

" XII. Simple Electro-positive Substances 114 

» XIII. Hydracids 123 

» XIV. Nitrogen 128 

M XV. Nitrogen and its Compounds 140 

" XVI. Carbon 144 

" XVII. Compounds of Carbon with Hydrogen 157 

" XVIII. Compound of Carbon and Nitrogen 166 

»* XIX. Silicon. Phosphorus 174 

*» XX. Sulphur 186 



IV CONTENTS. 

PAOE. 
CHAP. XXI. General Observations upon the Metals. First Class of Metals, or 

those which form Acids with Oxygen 197 

" XXII. Second Class of Melals. Alkaline Metals, or those whose Ox- 
ides are fixed alkalies, or alkaline earths. Order I. Metals 

which, with Oxygen, form the fixed alkalies 211 

" XXIII. Second Class of Metals. Order II. Metals which, with Oxygen, 
form alkaline earths. Barium. Strontium. Calcium. Magne- 
sium ■ 218 

" XXIV. Third Class of Metals. Earthy Metals, or those whose Oxides are 

earths 224 

" XXV. Fourth Class of Metals. MetaU whose Oxides are not regarded as 

acids, alkalies, or earths 229 

" XXVI. Fourth Class of Metals continued 235 

" XXVII. Fourth Class of Metals continued 244 

"XXVIII. Crystal izatiou. Classification of Salts. Salts of the Oxacids 254 

" XXIX. Salts of the Oxacids continued. 267 

» XXX. Salts of the Hydracids or Hydrosalts 277 

PART III. 

CHAPTER XXXI. Considerations on the subject of Organic Chemistry. Vegeta- 
ble Chemistry. Proximate Principles and Ultimate Ele- 
ments. Vegetable Acids. 284 

" XXXII. Vegetable Alkalies, Oils, Resins, &c 293 

" XXXIII. Alcohol, Ether, &c 301 

XXXIV. Sugar, Starch, Gum, &c 305 

» XXXV. Fermentatiou 319 

" XXXVI. Animal Chemistry, or Animal Organic Bodies 323 



PREFACE 



Chemistry is a most comprehensive science ; — while it in- 
structs the philosopher in the constitution of matter, it teaches 
man how to perform the most common operations in the busi- 
ness of life, such as the preparation of food, the warming and 
ventilation of apartments, soap making, washing, &c. The arts 
of dyeing, glass making, engraving, and of preparing medicines, 
have their foundation in chemical science. 

From the intimate connection which subsists between the 
different branches of Physical Science, the Author of this work 
has been naturally led from the study of one, to that of others ; 
and the pleasures and advantages she has derived from these 
pursuits, have induced the desire that they might be more gen- 
erally appreciated and enjoyed, especially by her own sex. Her 
series of works on Botany, Natural Philosophy, Chemistry, and 
Geology, she is happy to believe, have been studied by many 
who would not have felt the courage to encounter more erudite 
works. Teachers, diffident of their own acquirements, have 
been taken by the hand, and guided, along with their pupils, in 
paths which the Author had labored to free from difficulties. It 
is pleasant, to reflect that we are companions of the young 
in their search after knowledge, and that our thoughts thus be- 
come incorporated with their thoughts, when the mind, yet 
free from prejudice, is open to the reception of truth ; — it is a 
still higher satisfaction to believe that while imparting to the 
young mind scientific truths, we may be instrumental in im- 
planting the seeds of piety, to be developed with the mental 
germination, so that the blossoms of the intellect, may be ac- 
companied by the fruits of the soul. 



CHEMISTRY 



CHAPTER I. 
INTRODUCTORY. 

GENERAL VIEWS OF PHYSICAL SCIENCE. APPLICATIONS OF 

CHEMISTRY. 

1. The Physical Sciences are so intimately connected that 
the study of one throws light upon the others. Natural Philoso- 
phy, Natural History and Chemistry are sister sciences pos- 
sessing many characteristics in common, but each distinguished 
by peculiar traits. 

2. The object of all the Physical Sciences is the investigation 
of the material world. No object is too vast for the grasp of 
science, none too small for its observation. The celestial orbs, 
the lowly flowret and minute insect, are, alike, objects of scien- 
tific research ; and all, in their own peculiar way, proclaim, 

" The hand that made us is divine." 

3. Let us imagine the three sister sciences surrounded by the 
objects of their several researches ; — We see Philosophy turning 
from the contemplation of the heavenly bodies, to cast an approv- 
ing look upon the steam-engine, and mechanical powers, or to 
examine with her optical glasses the structure of a mite, or some 
object in the far distant regions of space. Natural History, the 
priestess of nature, crowned with the powers of all climates, calls 
around her all animated things, whether of the earth, the air or 
sea. She also claims as hers the rocky foundation of the earth, 
its metallic treasures, the diamond of the mine, and the ocean's 
pearl. 

4. And what of all that is above, upon, or under the surface 
of the earth, belongs to Chemistry since her sister sciences have 
appropriated to themselves the works of nature and of art X 
Chemistry claims the elements, of which all material substances 

1. Connection of the Physical Sciences. 

2. Their object and scope. 

3. The sister sciences. 

4. Province of Chemistry. 



8 INTRODUCTORY. 

are composed ; she, under the direction of their great Creator, 
presides over their combination, and, at the appointed time, 
effects their dissolution, carefully garnering up her atoms, so 
that not one shall be lost. Chemistry, then, may be imagined 
as veiled from observation, and carrying on those secret processes 
of composition and decomposition which are intimately connected 
with the operation and suspension of the vital powers in plants 
and animals. In obedience to her laws, inorganized matter as- 
sumes various forms of beauty and regularity, . as in crystals 
and diamonds, and, at her command, the hardest rocks crumble 
into dust. 

5. The question is often asked, " does the study of the sciences 
tend to establish the mind in the truths of religion, and promote 
christian humility ; or, rather, does not science put nature in 
the place of God, and heighten the pride of man, by filling him 
with lofty notions of his own powers, which can thus penetrate 
the mysteries of creation 1" We answer that such effects may 
arise from a superficial study of the sciences — he, who looks 
not beyond nature, to nature's God, who seeing a little, believes 
that he sees all of the mysteries of creation, cannot truly be 
called a philosopher. The discoveries of science demonstrate 
the existence of physical laws which must have originated in 
one Omniscient and Omnipotent mind ; — they exhibit nature as 
the mere creation of Almighty power, subservient to his will, 
and governed by his laws. Man, by the light of science, beholds 
himself as an atom in creation ; even his discoveries humble 
him ; for the more he learns of the wonders of nature, the more 
extensive seem the fields yet unexplored, and the more humble 
his own attainments. 

6. It is the office of science to explain appearances, and to teach 
man to distinguish them from reality. Thus, we learn from 
Astronomy that the apparent motion of the heavenly bodies is 
not real, but caused by the motion of the earth ; we learn from 
Optics, that we do not see the real object before us, but its image 
depicted on the back part of the eye, and, there, contemplated 
by the mind. Chemistry proves, that what appears to be the 
destruction of matter is not such ; but, that when a body seems 
to undergo a process of dissolution, its particles are only set free 
to enter into new combinations, and that no atom, which has 
been created, is suffered to be lost. 

5. Effects of the study of the sciences upon the human mind. Religious 
influence of science. 

6. Science teaches to distinguish the apparent from the real. That mat- 
ter is indestructible. Combustion not the destruction of atoms, but of 
combinations. 



INTRODUCTORY. 9 

7. Inquiries into the nature of compounds, and the various 
changes of which matter is susceptible, must be deeply interest- 
ing to every intelligent mind. But it is not alone for thepleasure 
of science that its pursuits are recommended j nor can we assent 
to the definition of a writer on Political Economy,* viz ; " that 
a philosopher is a person whose trade it is to do nothing, and 
speculate on every thing." Chemistry is not merely a grave 
pastime for philosophers ; it bears an important relation to the 
useful arts ; and most of the inventions of modern days owe 
their origin to this science, or depend on principles which 
Chemistry alone can explain. 

8. Art and science are mutually dependent on each other ; the 
former works, the latter thinks. It would be as absurd to con- 
tend which is the more useful to society, the working man or 
the thinking man, as whether the hands or the brain are the 
more necessary in effecting mechanical operations. Thinking 
and working should go together ; the more the working man 
thinks, or in other words, the more he combines science with 
mechanical skill, the more likely will he be to excel, and to im- 
prove on what others have done. The man of science who is 
skillful in manual operations, possesses a great advantage in 
being able to adapt to their proper use, his instruments of ob- 
servation and experiment, to supply their deficiencies, or to 
invent new instruments. 

9. Mechanical operations are a series of philosophical experi- 
ments. The soap boiler, in combining oil and water through the 
medium of an alkali, illustrates on a large scale the doctrine of 
Chemical Affinity. The glass maker exhibits chemical pheno- 
mena, in melting together, and combining alkaline, saline, 
metallic and earthy materials ; in the effect of coloring matter 
upon the compounds thus formed ; and in cutting, grinding and 
polishing glass. The tanner, by a chemical process, converts 
the soft spongy skins of animals into leather, which is hard, 
tough, and impervious to water. The farmer in manuring his 
grounds, and in mixing soils of different kinds, is working on 
principles which he can only understand by a knowledge of the 
effects of chemical combinations. The physical sciences and the 
arts of life, must go, hand in hand, in the work of improvement. 
Every advance in science gives a new advantage to the arts ; 
and every improvement in the arts offers to science a fresh field 

•Smith, See Wealth of Nations, Book I, Chap. 1, p. 15. 

7. Relation of Chemistry to the useful arts. 

8. Mutual dependence of art and science. 

9. Common operations effected on scientific principles. Soap boiling- 
Glass making— tanning, &c. 



10 INTRODUCTORY. 

of research, and new facilities for discovery. Thus, the philoso- 
pher and the artisan are mutually dependent on each other. 

10. The process of bleaching linen and cotton was long and 
laborious, requiring weeks and even months for its completion, 
until by the discovery of chlorine, the manufacturer was present- 
ed with a liquid, which, by immersing the cloth in it for a few 
hours, produced the necessary effect. The same chemical agent, 
chlorine, is most usefully employed as a purifier of infected 
atmospheres, thus preventing the contagion of dangerous dis- 
eases. 

1 1. The discovery of iodine may be traced to the observation 
of a soap boiler. In the refuse of soap ley, he discovered cer- 
tain corrosive properties for which he could not account. He 
applied to a Chemist, who, on subjecting the substance to analy- 
sis, discovered a new and important chemical element which he 
named iodine. 

12. A striking instance of the benefits of science, in alleviat- 
ing human suffering, is to be met with in the needle manufacto- 
ries, of England. The workmen are obliged to breathe an at- 
mosphere filled with minute particles of steel, which fly from 
the grindstones, used in pointing the needles. The irritation 
produced by this dust on the lungs caused consumption. Various 
expedients were resorted to ; but no gauzes or screens could ex- 
clude this fine and penetrating dust. At length the magnetic 
influence was resorted to, and masks of magnetized steel wire 
gauze were constructed ; the floating atoms of steel being thus 
arrested, the workman now breathes freely, in the assurance 
that he is not inhaling a fatal atmosphere. 

13. The safety lamp, the lightning rod, the life boat, are gifts 
presented to man by science. Chemical science, is not only 
deeply interesting, as unfolding the laws and secret operations 
of nature ; but eminently useful, considered in its relation to the 
diseases and wants of man and the progress of human improve- 
ment. 

14. Scientific pursuits exercise on the mind itself, a healthful 
and invigorating influence, by bringing into action aud disciplin- 
ing the intellectual powers. In considering the variety of the 
works of creation, the grand and the minute so harmoniously 
combined, and the system by which the whole universe is con- 
nected in an infinite series of relations ; in observing the readi- 

10. Practical applications of chlorine. 

11. Discovery made by a soap boiler. 

12. Application of the magnetic power. 

13. Other applications of scientific discoveries. 

14. The mind of man adapted to the study of nature. 



INTRODUCTORY. 11 

ness with which the human mind seizes upon facts which unfold 
these dependencies and relations, and the elevation and enlarge- 
ment which such studies give to the soul, we are led to believe, 
that, as the earthly parent surrounds his child with the instru- 
ments and means of knowledge, so our Almighty Father made, 
beautified and enriched the material world, that He might thus, 
give lessons of wisdom to His children, and afford scope for the 
intellectual energies with which he had endowed them. 

15. Chemistry begins where the other physical sciences end 
For example, Natural Philosophy considers the mechanical prop- 
erties of matter ; Natural History examines the external organs 
or form of objects, with a view to their classification j while 
Chemistry, penetrating to their internal particles, examines 
their constitution. 

16. Chemistry teaches the elements of which matter is com- 
posed, the properties of these elements, and their laws of combina- 
tion; it also shows what are the component parts and properties 
of compound substances. 

17. The foundations of chemical science are observation, ex- 
periment and analogy. By observation, facts are noted and im- 
pressed on the mind ; by experiment, new facts are brought to 
light ; by analogy, we infer what is unknown from what is known. 
Thus, suppose a person to notice that when a certain vegetable 
substance, which is common in brooks and ponds and grows 
under water, is exposed to the sun, globules of air appear on its 
filaments, while no such globules of air are seen upon the weeds 
which are in shade. This is an observation. The observer, by 
inverting over it a wine glass filled with water, sees this air rising 
up through the water until it fills the glass. Having now se- 
cured a portion of the air, he is ready to try an experiment upon 
its nature. On introducing a burning taper into it, he finds that 
the taper burns with greater brilliancy and fierceness than in 
common air. He has now ascertained that this air differs from 
the common air. He is then led by analogy to inquire, whether 
other green vegetables will not, in similar circumstances, give 
off air of the same kind. In this way we may suppose oxygen 
gas, might have been observed, experimented upon, and finally 
found to exist in a great variety of substances. 

18. All the knowledge we possess of external objects is found- 
ed upon experience ; this furnishes facts, and the comparison of 
these facts establishes relations. Such inductions, connected 

15. Distinction between the physical sciences. 

16. Definition of Chemistry. 

17. Foundations of chemical sciences. Definition of certain terms. 

18. Process in the discovery of general laws. 



12 INTRODUCTORY. 

with the intuitive belief that the same causes will produce the 
same effects, lead to the knowledge of general laws, and these 
laws constitute a science. Thus has Chemistry, beginning with 
scattered and isolated facts, advanced to its present distinguished 
rank among the sciences. 

19. The properties of matter are either Physical or Chemical ; 
the former are considered in Natural Philosophy, the latter in 
Chemistry. 

20. The attraction of gravity or of large masses, has no in- 
fluence in chemical action ; but, chemistry exhibits another 
species of attraction, called affinity, which operates only between 
the minute particles of matter. 

21. Heat, Light and Electricity have important influences 
upon chemical combinations ; as they have not been proved to 
be ponderous or to have weight, they are called imponderable 
agents, the consideration of these agents, together with the laws 
of affinity, will constitute the First Part of the following works ; — 
Part Second will treat of the chemical elements of ponderable 
matter ; or Inorganic Chemistry ; Part Third will explain the 
chemical constitution of vegetable and animal substances, the 
study of which, constitutes Organic Chemistry. 

19. Properties of matter. 

20. Difference between the attraction of gravity and that of affinity. 

21. Division of subjects. 



PART I. 

HEAT, OR CALORIC. 
CHAPTER II. 

GENERAL REMARKS ON THE IMPONDERABLES. HEAT. EXPANSION 

BY HEAT. THERMOMETERS. 

22. The imponderable agents have a very important influence 
over all terrestrial matter. These agents are Heat, Light and 
Electricity, which last includes Galvanism. 

23. It is not known whether these agents are strictly material substances, 
or only motions or affections of matter. We cannot confine and exhibit 
them as we can other material bodies, nor do the most delicate balances 
show that they possess weight. It is thought by some, that since we cannot 
prove these agents to possess the common properties of matter, they ought 
not to be regarded as material existences. Some philosophers are of opinion, 
that they are merely the effects of vibratory and rotatory motions among 
the particles of matter ; and that their intensity depends on the velocity of 
their motions. 

But whether they be material existences, or only properties of matter, 
they are found to be subjected to physical laws. We shall therefore, con- 
sider them as invisible fluids, pervading nature, and requiring only the 
intervention of other kinds of matter to render them evident. 

HEAT, OR CALORIC. 

24. Heat, in common language, is used to signify both cause 
and effect. By caloric* chemists understand the cause of which 
heat is the effect ; it is the agent which produces in our minds, 
by means of external organs, the sensation of heat. The term 
igneous fluid, matter of heat, Sec, mean the same as caloric. 

25. Caloric is a subtle, invisible fluid, universally diffused, 
and highly elastic, that is, composed of particles that strongly 
repel each other, but possess an attraction or affinity for all 
other substances. 

26. There are six sources of caloric, viz. 1. the Sun : 2. Com- 

* From color, a Latin word signifying heat. 

22. Imponderable agents. 

23. Different opinions with respect to the imponderable agents. 

24. Definition of caloric. 

25. Nature of caloric. 

26. Sources of caloric. Mechanical means of producing heat. 

2 



14} EXPANSION OF BODIES BY HEAT. 

bustion: 3. Electricity : 4. The bodies of living animals : 5. Chemi- 
cal action: 6. Mechanical action. The mechanical means of 
producing heat are friction and percussion. 

The rubbing together of two pieces of wood is an example of friction, and 
the hammering a piece of metal, of percussion. By these means, wood and 
other combustibles may be set on fire : and many serious accidents have 
occurred in consequence, as the burning of factories, explosion of powder 
mills, and the like. 

27. Caloric is capable of two modes of existence ; in the one, 
it is manifested to the senses, and its degrees of intensity may- 
be measured by means of certain instruments. When in this 
state, it is called free caloric, sensible heat, caloric of temperature, 
&c. In the second case, the caloric is concealed from the senses, 
and is said to be latent or hidden. 

Expansion. 

28. One of the most important and universal effects of caloric 
is, to expand all bodies into which it enters ; and that such is the 
effect of caloric is proved by the fact, that a body so expanded 
returns to its original bulk on cooling. 

Experiment. Let a small bar or cylinder of iron, a, be fitted to pass 

through the aperture at 
Fig. 1. b and let its length be 

such that it will fit into 
the notch c. On being 
heated, it will be found 
too large to pass through 
the aperture at b, and too 
long for the space c ; when cooled it will contract to its original dimensions. 

29. A very useful application of this principle is familiar to wheel wrights. 
It is highly important that the parts of a carriage wheel should be united 
in the firmest possible manner. For this purpose, when the wooden por- 
tions have been nicely joined, the iron band is constructed so small, that it 
cannot be forced on when cold. The band now being made red hot, it ex- 
pands, so as readily, to encompass the wheel ; and in cooling, it contracts, 
compressing and binding the parts and joints together with an immense 
force. 

30. It is supposed that caloric causes expanson, by insinuating 
itself between the particles of a substance, and driving them by 
its elastic force, to a greater distance from each other. Thus, 
a body when heated occupies greater space, and is of a less 
specific gravity, than when cold. 



27. Free and latent heat. 

28. Caloric expands bodies. Experiment to show the expansion of a solid 
body by caloric. 

29. Application of this principle in the manufacture of carriage wheels. 

30. Manner in which caloric causes the expansion of bodies. 



HEAT. 15 

31. It might be inferred a priori * that the expansive effect 
of caloric would be opposed by the cohesive attraction of the 
particles ; and accordingly we find cohesion and caloric, univer- 
sally acting as antagonists to each other. 

Bodies exist in the solid, liquid or gaseous state, according 
to the prevalence of the cohesive or repulsive forces. In solids, 
the power of cohesion, is greater than that of repulsion, and the 
particles are held closely together. In liquids, the cohesion is 
so far overcome, that the particles can move freely among them- 
selves ; and in aeriform bodies, though cohesion undoubtedly 
exists, it is not apparent, on account of the predominance of the 
repulsive power. We should hence expect, that with the same 
addition of caloric, liquids would expand more than solids and 
gases more than either, and this is practically true. 

32. It is demonstrable, that some bodies expand much more than others 5 
and that when any solid is heated gradually, through any range of tempera- 
ture, the hotter it becomes, the more it expands by the same acquisition of 
heat. For instance, if a metallic rod of known dimensions, be heated from 
60° to 100° it will expand to a certain degree. If now another 40° of heat 
be applied to it, the increase of its dimensions will be greater than in the 
former case. And this is easily explained ; for the cohesion being partially 
overcome by the first addition of heat, the second portion will have less op- 
position to encounter and will produce a proportionally greater effect. 

33. By the application of various degrees of heat, solid bodies 
may all, or nearly all be converted into liquids, as in the melting 
of ice, the fusion of wax, metals, &c. Liquids, by the further 
addition of caloric, may be converted into gases. 

34. An instrument called the pyrometer, f has been invented 
to show the degrees of intense heat, above those which we are 
able to estimate by the mercurial thermometer. Mercury boils 
and becomes vapor, at 660° ; above that point, therefore, it is 
incapable of measuring heat. The pyrometer depends for its 
operation, on the expansion of metals, and shows the different 
degrees of expansibility of different kinds of metals. 

The figure shows a rod of metal, A A, resting horizontally upon support- 
ers. One end of the rod is fixed, the other end touches the wheel work, 
B B, which is so connected with the index C that a slight motion of the 
wheels, causes a considerable movement in the index. The rod of metal, 

* By a priori is meant, beforehand, or prior to any reasoning or experi- 
menting, on the subject, 
f From the Greek pur, fire, and metron, measure, signifies^re measurer. 

3 1 . Expansion opposed by cohesive attraction. Why liquids expand more 
than solids, and gases more than either. 

32. Expansion greater at certain stages of heat, with an equal increase 
of caloric, than at other stages. 

33. Effects of heat in changing the state of bodies. 

34. Pyrometer. Its use and construction. Describe the figure. 



16 



PYROMETER. 

Fig. 2. 




on being heated by the lamps 1, 2, 3, expands and presses against the wheel, 
which communicates motion to the index. The more expansible is the 
metal, the farther the index will move on the plate. 

35. The pendulum of a clock, in order to vibrate seconds, 
must always be of a given length ; but as metals expand with 
heat, the pendulum is liable to shorten in winter and lengthen 
in summer : — it follows that the clock will go faster in winter 
than in summer. By lengthening or shortening the pendulum, 
this evil may be remedied. About thirty-nine inches is found 
to be the length necessary for a pendulum to vibrate seconds. 
It may be readily understood why a short pendulum should 
Fig. 3. vibrate faster than a long one, 

when it is considered that the 
pendulum is the radius of a cir- 
cle, which circle is larger or 
smaller, according to the length 
of the radius. Thus suppose A 
and B to be two pendulums, of 
which B is the longer. B must 
describe the arc, c, d, of a circle, 
while A only describes the arc 
from e to f. 
36. Various circumstances have rendered it most convenient to construct 
pendulums of metal, though their liability to expansion and contraction by 
change of temperature, is an imperfection. If the temperature of the pen- 
dulum be raised, its dilatation will evidently remove its mass farther from 
the point of suspension, and will cause its rate of vibration to be slower ; 
while the diminution of temperature will be attended with the contrary effect. 

35. Why will a clock go faster in winter than in summer ? How may 
this evil be remedied ? Why does a short pendulum vibrate faster than a 
long one ? 

36. Effect of expansion and contraction upon the balance-wheel of a 
watch. 




HEAT. 



17 



Thus it would follow, that with every change of weather the rate of the 
clock would vary. In like manner, the swinging motion which the balance 
wheel of a watch receives from the hair spring which impels it, depends on 
the distance of the metal forming the rim of the wheel from its center. If 
this distance be increased the spring acts with less advantage on the mass 
of the wheel, and therefore moves it more slowly ; and if it be diminished, for 
a similar reason, it moves more quickly. It follows, therefore, that when 
a wheel expands by increased temperature, the rate of vibration will be dimin- 
ished ; and when it contracts by diminished temperature, the rate of vibration 
will be increased. A watch for the same reason, will fluctuate in its rate of 
keeping time with every change of temperature. Various ingenious inven- 
tions have been resorted to, to compensate for the irregularities, occasioned 
by increased or diminished temperature upon the metallic rod of the pendu- 
lum, or balance wheel of a watch. 

Expansion of Liquids. 

37. Liquids, like solids, differ greatly in their several expansi- 
bilities by heat. In general, the less the heat requisite to boil a 
liquid, the more it will expand by a given increase of temper- 
ature. And further, liquids like solids are subject to an increas- 
ing rate of expansion, as the heat is raised higher. 

Experiment. Fill to o, o, ^ *£• *• 

two small matrasses, the one 
with alcohol, the other with 
water ; place under each, a 
pan of burning charcoal, or 
immerse the bulbs in boiling 
water. The alcohol will 
rise to a, while the water is 
at w. 

On cooling, the liquids will 
gradually return to their original 
bulk. As a general rule, those 
liquids expand the most uniformly 
through a steady rise of temper- 
ature, which require the strong- 
est heat to make them boil. Al- 
cohol boils with a lower degree 
of heat, than water ; it is, there- 
fore, exceedingly expansive ; and 
the nearer it approaches the boil- 
ing point, the more rapidly its volume increases. 

38. Since expansion by change of temperature changes the 
weight of a given bulk of a liquid, and this change of weight is 
in the inverse proportion to the expansion, it follows, that all the 




37. Liquids vary in their capacities of expansion by heat. Experiment to 
show the different effects of heat in the expansion of alcohol and water. 
General rule with respect to the expansion of liquids. 

38. Manner of determining the degrees of the expansion of liquids. 

2* 



18 



EXPANSION OF LIQUIDS. 



ordinary methods for determining the specific gravities of liquids 
may likewise be applied to determine their degree of expansion. 
The specific gravity of the same liquid at different temperatures 
is different, and always in an inverse proportion to the expansion : 
the less the specific gravity, the greater, in the same proportion, 
will be the expansion. 

39. The French Chemists have determined the absolute expansion of 
mercury by means of an apparatus here represented, and which may be 
applied in the same manner in the case of other liquids. It depends on the 
hydrostatical principle, that two vertical columns of liquid communicating 
by a horizontal tube, will have heights in the inverse proportion of their 
densities. 



A T and A' T' 
represent two ver- 
tical tubes of glass, 
which communi- 
cate with a hori- 
zontal tube P P. 
They are filled with 
mercury to the 
height nn. So long 
as the temperature 
is the same in every 
part, the surfaces 

of the mercury in the two vertical tubes must stand at the same level : but 
if the mercury in one tube, be reduced to the temperature of melting ice, 
and in the other be of a higher temperature, the expansion produced by the 
higher temperature, will cause the mercury in one tube to dilate in a greater 
degree than in the other, and to become specifically lighter ; still the columns 
balance each other, the column of mercury in the tube .4' T will balance the 
lower column in the tube A T, at the lesser temperature. 

Exception to the general law of Expansion. 

40. To the general law of expansion by heat, and contraction 
by the loss of it, water furnishes a most remarkable exception. 
On cooling water at the common temperature, it will be found 
to contract gradually until it is about 40° when it begins to 
expand until it becomes ice. Water, in becoming ice, increases 
in bulk ^ ; water in freezing becomes crystallized ; the particles 
begin to change their positions, shooting out into needles and 
crossing each other at various angles, as may be seen when 
water is freezing in a shallow vessel. It is supposed that this new 
arrangement of particles is the cause of its increasing in bulk, 
and the supposition is supported by the facts, that solutions of 




39. Describe the apparatus for determining the absolute expansion of 
mercury or other liquids. 

40. Effect of cooling water below 40°, Change which takes place at thia 
temperature, and probable cause of this change. 



HEAT. 



19 



salts, in crystalizing are enlarged in bulk, and that several of the 
metals on solidifying after fusion, also expand, taking, at the 
same time, a crystaline structure. This property renders anti- 
mony so useful for casting types, and cast-iron for various 
utensils, as the metal on cooling, perfectly fills the mould ; 
whereas, if they followed the general law of condensing by the 
loss of heat, they would shrink, and receive an imperfect im- 
pression. 

41. In the economy of a wise and good Providence, this pro- 
perty of water has very important consequences ; for if ice were 
heavier than water, the lakes, rivers, and even the ocean itself, 
in cold countries would become solid ice, and all animal life 
which now exists within them would be destroyed. It appears 
a wonderful provision of Almighty wisdom, that, for the con- 
venience and preservation of man and animals, water should be 
almost the only substance which does not continue to become 
heavier as it grows colder. 

Fig. 6. 
42. Let a a f represent two ves- 
sels filled with water at the tem- 
perature of about 66° ; b b 1 are 
tin trays surrounding the upper 
part of one vessel, and the under 
part of the other, and filled with 
a freezing mixture, viz., ice and 
salt. The first effect of the cold 
is to reduce the temperature of | 
the whole mass of water to 40°, 
at which point water is at its 
greatest density. After this, 
the cooling process in the vessel c, will be limited to the surface, where the 
temperature will gradually fall to 32°, at which point the water will freeze ; 
for the freezing water, being lighter than the water below, will remain on 
the surface. This is what takes place in lakes and large bodies of water. 

In the vessel a', where the cold is applied at the bottom, the effect is very 
different ; for the water when cooled below 40° becomes lighter and rises, 
the warmer or heavier portions descend, in their turn become cooled, and 
again rise; other, successive portions follow the same course, until the 
whole, being reduced to 32°, or the freezing point, hardens into one solid 
body of ice. The process described in the vessel a, or where the cold is at 
the surface, is that which goes on in nature ; that in the vessel a', is what 
would take place, did not water, unlike all other known substances, become 
lighter before it freezes, so that a stratum of ice-cold water at 32°, lies over 
a mass of warmer water at 40°. 

43. The force with which water expands in freezing is im- 
mense, bursting not only earthen and glass vessels, but even 




41. What would be the effect of cold on lakes and rivers if water became 
heavier as it changed to ice ? 42. Exp. 
43. Expansive force of freezing water. 



Fig. 7. 



20 EXPANSION OF AERIFORM BODIES. 

cannon and strong metallic vessels, and causing chasms in rocks. 
By this expansion water pipes are also burst, and pavements 
thrown up. 

Expansion of Aeriform Bodies. 

44. In their expansion by heat, aeriform bodies differ from 
liquids and solids in three important points, viz ; — 

1st. Aeriform bodies expand 
more than liquids and solids with 
the same increase of temperature ; the 
cohesion of their particles being 
already more than counterbalanced. 

2nd. They expand equally. 

3d. They expand uniformly 
through all temperatures. 

45. Experiment 1st. Hold, near the fire, 
a bladder partially inflated. The air with- 
in, being expanded by the heat, will soon 
distend the bladder. 

Experiment 2nd. Place an empty 
thermometer tube (Fig. 7.) with its open 
end in a glass of water, and apply the 
hand to the bulb a ; the heat of the hand 
will cause the air within the bulb to ex- 
pand so that a portion will rush out and 
rise in bubbles through the water ; on re- 
moving the hand from the ball, the water 
will rise in the tube to fill the vacuum 
caused by the condensation of the air. 

Thermometers. 

46. The senses being very fallible means of measuring heat, 
the wants of science demanded the invention of some instrument 
for that purpose. About the middle of the seventeenth century, 
the Florentine Academicians made an attempt towards such an 
invention ; their imperfect thermometer consisted of a glass tube, 
with a bulb at one extremity, filled to a certain mark with alco- 
hol, and closed at the open end ; — the expansion of this liquid, 
or its rise above the mark, indicated heat ; and its contraction, or 
fall below the mark, indicated cold. This instrument, called the 
Florentine glass, was introduced into England by Boyle. At 

44. Particulars in which aeriform bodies differ from liquids and solids in 
their expansion by heat. 45. Exp. 

46. Why was the invention of the thermometer important ? First attempt 
towards the construction of the thermometer. 




HEAT. 



21 



first, the supposition that a liquid could contract and expand in 
a tube closed at both ends, was ridiculed as absurd, and it was 
not until the philosophers of the day were convinced by the 
experiments of Boyle, that this fact was admitted. 

47. The invention of the first thermometer,* is usually as- 
cribed to Sanctorius, an Italian ; this instrument depended for 
its effects on the expansion of air by means of heat. 

If a matrass be held in both hands by its Fig. 8 * 

bulb, the warmth communicated will expand 
the air within, and expel a portion of it. Now 
immerse the mouth of the instrument in a ves- 
sel containing a colored liquid, (see Fig. 8.) 
and remove the hands ; the air will gradually 
cool and contract, while the liquid will rise 
into the tube, to supply the place of the air 
which was forced out. The apparatus in this 
condition, constitutes the Air Thermometer of 
Sanctorius. On the approach of a heated 
body to the bulb, the expansion of the enclosed 
air drives down the liquid in the tube ; thus, 
the lower the column of liquid, the greater is 
the degree of heat indicated ; this is the re- 
verse of what takes place in the common mer- 
curial thermometer, where the greater the 
height of the column of mercury, the greater 
is the degree of heat signified. 

The superior advantages of the air ther- 
mometer, consist in the great expansive property of 'air by which minute changes 
of temperature are rendered obvious. But this advantage is outweighed by 
the objections, that so great an expansion of air with a slight degree of heat 
would require an unmanageable length of tube for observing any consider- 
able increase of heat ; and that the variable pressure of the atmosphere in- 
fluences air, independently of temperature, so that the air thermometer can 
only be depended on when the barometer stands at a fixed point. 

48. A modification of the air thermometer, invented 160 years ago, by 
Sturmius, and revived by Prof. Leslie, in 1804, is extremely useful in some 
experiments. It consists of a glass tube, (Fig. 9.) bent like the letter U, 
and having a bulb, a and b, at each extremity. It contains a colored liquid, 
commonly sulphuric acid, tinged with cochineal. If heat be applied to 
one of the bulbs, as at a, it will expand the air within, causing the descent 
of the liquid in one branch, and its ascent in the other towards 6. The 
distance the liquid moves, is measured by a scale attached to one of the 
branches, and divided into equal parts, called degrees. It is obvious that, 
with this instrument, we can only learn the difference of the temperature 
of the two bulbs. On this account, it is called the Differential Thermometer. 

* From the Greek iherme heat, and mefrm measure, meaning an instrument 
to measure the degrees of heat. 

47. Thermometer of Sanctorius. What causes the liquid to descend in 
the tube on the approach of a heated body while in the mercurial thermom 
eter, the column of mercury rises under the same circumstances ? 

48. Leslie's Differential thermometer. 





DIFFERENTIAL THERMOMETER. 

Fig. 9. 49. Howard's differential Thermometer is 

very delicate. In form and principle, it 
resembles that of Leslie ; but the fluid it 
contains, is sulphuric ether, an extremely 
volatile substance. One of the bulbs is 
left with a minute opening, and a sufficient 
quantity of the colored ether being intro- 
duced, it is then boiled. The vapor of 
ether now rises and fills the tube, expelling 
the air through the aperture. While the 
ebullition is going on, and the tube is full 
of vapor, the opening is suddenly closed by 
fusing the glass.* The etherial vapor now 
indicates the changes of temperature, as 
the air does in the thermometer of Leslie, 
but as the vapor expands in one branch, it 
causes a pressure on that in the other, and 
the latter becomes liquid ; thus relieving the 
countervailing pressure which would im- 
==- -^ pede the motion of the ether, if the second 
jr^=^s bulb contained an incondensible gas or 
vapor. 

50. As air is not extensively applicable for the purpose of a thermometer, 
and as the small expansibility of solids renders them almost useless for this 
purpose, Chemists have sought among liquids for one, combining the most 
advantages, with the fewest objections. It is evident that perfect fluidity 
and freedom of motion are essential ; oils and viscid liquids, therefore, are 
unfit, though a thermometer of the former was recommended by Newton. 
To be of extensive application, also, the liquid should be one which boils 
with great difficulty ; for its indication can be taken only while it retains 
the liquid state ; and, for the same reason, it should be able to support a 
great degree of cold without freezing. Its expansion, also, should be as 
nearly as possible uniform, through a great range of temperature. Mercury 
or quicksilver, though far from perfect, possesses the necessary requisites in 
a higher degree than any other known liquid, and is, therefore, in general 
use as a thermometer. 

51. The principle scales in use, are 1st. The centigrade, or that of Cel- 
sius, used principally in France and Sweden, and generally known over 
Europe. Of this scale the freezing point is marked 0°, and the boiling 
point 100°. 2nd. The scale of Reaumur, used in France before the revo- 
lution, and still retained in Spain, on which the freezing point is at 0°, and 
the boiling point at 80°. 3d. That ofDe Lisle, the use of which is confined 
to Russia ; this is a descending scale, the boiling point being 0° and the 
freezing point 150°. 4th. The scale of Fahrenheit which is used in this 
country, Great Britain, and Holland. On this the freezing point is marked 
32°, and the boiling point 212°, the intermediate spaces containing 180 equal 
parts or degrees. 

* Glass tubes thus closed, are said to be hermetically sealed. 



49. Howard's Differential thermometer. 

50. Objections to air and solids for extensive use as thermometers. Why 
oil is unfit. Requisites in a liquid to be used for this purpose. What liquid 
is then generally used for the thermometer ? 

51. Different thermometer scales in use. 



FAHRENHEIT S THERMOMETER. 



23 



52. A temperature expressed in degrees of one of the above scales is 
easily convertible to those of another, by applying the following rules. 

1st. To reduce any number of degrees of the centigrade scale to terms 
of Fahrenheit, multiply the number by 9, divide by 5, and to the quotient 
add 32. The converse process is as follows ; subtract 32 from any num- 
ber of Fahrenheit's degrees, multiply the remainder by 5, and divide by 
9; the quotient will express the same temperature in degrees of the cen- 
tigrade. 

Examples. Fig. 10. 

Centigrade. Fahrenheit. 

100°x9=900-s-5=180 add 32=212°. 



Fahrenheit. Centigrade. 

212°— 32=180x5=900^-9=100° 



2d. The degree of Fahrenheit being in length to that 
of Reaumur in the ratio of 4 to 9 ; to reduce an expres- 
sion of Reaumur's scale to one of Fahrenheit, we must 
multiply by 9, divide by 4 and add 32 ; and, on the con- 
trary, to obtain an expression by Reaumur's scale equiv- 
alent to a given one by Fahrenheit's, we subtract 32, 
multiply by 4 and divide by 9. 

Example. 
Reaumur. Fahrenheit. 

16x9=144-=-4=36° add 32°=68°. 
80°X9=720h-4=180° add 32°=212°. 

Fahrenheit. Reaumur. 

212°— 32=180x4=720^-9=80°. 
68°— 32=36x4=144^-9=16°. 

Thermometers are sometimes constructed with differ- 
ent scales affixed to the same tube, so that the corres- 
pondence of the degrees of different thermometers may 
be at once perceived. The figure represents a ther- 
mometer, with Fahrenheit's and Reaumur's scales. 

53. The mercurial thermometer is accurate 
in its indications of temperature, as high as 
212° ; for though mercury, like other liquids, 
expands proportionally more at high than at low 
temperatures, the irregularity is exactly com- 
pensated by the expansion of the glass tubes. 
But above 212°, the glass expands more rapidly 
than the mercury, and the indications are less 

52. Rule for reducing degrees of the centigrade ther- 
mometer to those of Fahrenheit, and for converting 
degrees of Fahrenheit to those of the Centigrade. Ex- 
amples. Rule for reducing degrees of Reaumur's ther- 
mometer to Fahrenheit's, and for converting degrees of 
Fahrenheit to those Reaumur. Examples. 

53. Irregularities of the mercurial thermometer. 





-60 



-# 



24 HEAT. 

accurate. This instrument may, however, be used for common 
purposes, to compare degrees of heat as high as 500°, and t is 
quite accurate as low as 39° below zero, when it freezes. 
When it is desirable to measure temperatures lower than 39°, 
alcohol must be employed. 



CHAPTER III. 

CONDUCTION OF HEAT. RADIATION AND REFLECTION. LATENT 

HEAT. LIQUEFACTION. FRIGORIFIC MIXTURES. 

Conduction of Caloric, or Heat. 

54. A piece of wood may be held in the hand, by one end, 
while the other is burning ; but if a bar of iron be heated at one 
end, the other will soon be too hot for the hand. This difference 
arises from the unequal facility with which bodies allow the 
passage of caloric through their masses ; or, in other words, from 
the unequal conducting powers of bodies. When a solid is heat- 
ed, the caloric is received by the particles nearest the source 
of heat, and transmitted to those next them, and so on, till it is 
diffused through the whole mass. 

55. Of all known bodies, metals transmit caloric the most 
rapidly ; they are, therefore, called the best conductors. 

Exp. Take four small rods ; one of metal, one of glass, one of wood, and 
one of whale-bone, and cement one end of each to a lump of sealing-wax ; 
then, successively expose each rod at the opposite end to the heat of a blow- 
pipe. The metal soon becomes so hot as to melt the sealing-wax from it : 
but the wood and whale-bone, may be destroyed by the heat, and the glass 
so heated, that it may be bent, while the sealing-wax at the opposite end has 
not become melted. 

56. Metals possess different conducting powers. 

Exp. 1st. Thus, if equal sized rods of several metals be coated with wax, 
at one extremity, and be equally exposed to heat at the other, the wax will 
melt upon some of the rods much sooner than upon others. 

Exp. 2nd. Let cones of different kinds of metals (see Fig. 11.) be sev- 
erally tipped with wax, and placed upon a heated metallic plate, the wax 
will first melt upon the one which is the best conductor of heat, and so on ; 
thus, showing the relative conducting powers of the different metals com- 
posing the cones. 

57. By some recent experiments, the conducting power 

54. Difference in the power of wood and iron to conduct heat. Manner 
in which caloric is transmitted in solid bodies. 

55. Best conductors of caloric. 

56. Metals vary in their conducting powers. Exp. 1st. Exp. 2nd. 






CONDUCTION OF HEAT. 25 

of several metals has been found to decrease Fig. 11. 
in the following order, viz., gold, silver, copper, * 

platinum, iron, zink, tin and lead ; the latter being mk 
the poorest conductor of caloric of all the metals, ^^jl^i^ 
Among bad conductors of heat are stones, dry wood, ■ 

charcoal, dry air, feathers, and other light animal and vegetable 
substances, particularly the usual materials for clothing. It is 
on account of the small conducting power of wool, cotton, &c, 
that they are chosen for their particular use ; for in summer, 
when the solar heat would scorch the skin, they impede its 
progress to the body, and in winter they retard the passage of 
heat from the body to the cold air. Wool is not so good a con- 
ductor as linen ; in a hot summers's sun, therefore, a white woolen 
dress is preferable to linen. Owing to the difference of their 
conducting powers, the different articles in a room, though 
really at the same temperature, will seem different to the touch. 
A marble slah will feel colder than a woolen carpet, because it 
absorbs heat more readily from the hand. For the same reason 
good conductors, when heated, transfer their caloric rapidly to 
the hand, and will therefore burn it, though a bad conductor, at 
the same temperature will scarcely feel warm. Thus coffee 
pots and other metallic vessels, intended to hold hot liquids 
have wooden handles. The conducting power of metallic ves- 
sels gives them an advantage over glass or earthen ware for 
heating liquids rapidly. 

58. The low conducting power of charcoal has given rise to a useful ap- 
plication of it in the Refrigerator* There are different kinds of this article ; 
a simple and useful one may be made as follows ; — procure a box of wood, 
divided by partitions of tin and iron, into three compartments. Inclose this 
box in one larger, by about an inch in each of its internal dimensions. The 
space between the boxes is to be filled with powdered charcoal. If meat, 
butter, wine, or other articles, be put into the two extreme compartments, 
and ice into the middle one, they may be preserved eool and fresh in the 
hottest weather ; for the charcoal scarcely permits the passage of caloric 
from without, while it is readily transferred through the metallic partitions 
from the meat &c. to the ice. A great saving is also effected in this way 
in the consumption of ice. In constructing ice houses, straw, which is an 
imperfect conductor of heat, is usually placed around the walls, roof and 
floor. A building made with double walls, having a space between them 
filled with air furnishes an excellent ice house ; for air where no source of 
radiation is present, is nearly impenetrable by heat. 

* Derived from the Latin, and signifies a cooler. 

57. Arrangement of metals according to their conducting powers. Why 
wool, cotton &c, are used for clothing. Why articles in the same room 
appear of unequal temperature. Why wooden handles are used for me- 
tallic coffee pots. Why metallic vessels are better than earthen for heat- 
ing liquids. 

58. The refrigerator. Ice houses. 

3 



HEAT. 



Conducting Power of Liquids. 

59. Liquids possess the power of conducting heat in a very- 
small degree. Heat applied to one proportion of a liquid is 
distributed through the mass, not by conduction, as in the case 
of solids, but by the motion of the particles. When heat is 
applied to the bottom of a vessel containing a liquid, the parti- 
cles nearest the source of heat become warm, expand, and being 
then lighter than the rest, rise to the upper surface ; the next 

stratum does the same, and so 
on till the whole is heated. But 
if the heat be applied at the 
top, the caloric will penetrate 
but a small distance downward. 
60. Exp. 1st. Let a be a glass 
vessel (Fig. 12.) nearly filled with 
water, and including an inverted air 
thermometer ; b a small dish contain- 
ing burning charcoal, and separated 
from the thermometer bulb by a thin 
stratum of water. While the surface 
of the water is heated to the boiling 
point, the thermometer below will 
indicate very little increase of tem- 
perature. 

61. Exp. 2nd. Let a 
and b (Fig. 13.) represent 
two thin glass tubes filled 
with water. If the heat 
of a lamp be applied to the 
bottom of the tube a, the 
whole mass of water 
within the tube will soon 
become equally heated, 
and begin to boil. But 
let the heat be applied 
near the top of the tube b, 
and the surface may be 
made to boil while the 
water at the bottom re- 
mains cold. The hot 
water being lighter than 
cold, it will remain at the 
surface ; while, if the par- 
ticles are heated at the bottom, they will rise by their specific levity, and the 
cold ones will descend to fill the vacuum. 




59. Mode in which heat is distributed through liquids. Why liquids do 
not become heated when caloric is applied to the upper surface. 

60. Exp. 1st. 

61. Exp. 2nd. 



EFFECT OF CALORIC ON AERIFORM BODIES. 



27 



Fig. 15. 




62. Exp. 3d. Fill a glass vessel with water, and throw into it a few 

Fig. 14. particles of amber, then apply heat to the bottom of the vessel; and 
a rising current will immediately begin in the center of the vessel, 
while descending currents appear at its sides, as represented by the 
direction of the arrows, (see Fig. 14.) It is by successive changes 
in the weight of the different particles of water, that the whole 
mass becomes heated. 

63. Oil is a bad conductor of heat. 
Exp. 4th. Let a b (Fig. 15,) 
represent a thin glass tube, two 
feet in length, closed at one 
end, and open at the other j 
pour into it two inches of pow- 
dered ice or snow, then upon 
this mass pour eight inches of 
oil, c ; and over this two or 
three inches of alcohol, d. The 

alcohol may be boiled, and even evapo- 
rated by the flame of a lamp, while the 

oil will not be sensibly heated, nor the 

frozen mass melted. 

As liquids are heated by internal 

motion, they must become cool in the 

same manner : and hence we see why 

soft solids and semifluids, like warm bread, puddings, &c. cool very slowly ; 

the internal motion of the particles being impeded, and the conducting 

power feeble. 

Effect of Caloric on Aeriform Bodies. 

64. Aeriform bodies possess the power of conducting heat, if 
at all, in a very slight degree. Like liquids they are heated by 
internal movements among their particles. 

65. When air is heated, currents are produced. In a heated 
room, the warmer air ascends, parts with caloric, and becoming 
heavier descends ; thus, there is an ascending and descending 
current continually in motion. If the door of a warm room be 
opened, warm air rushes out at the upper space, while cold air 
enters below. This may be proved, by holding the flame of a 
lamp at an open door : at the upper part of the door the flame 
will be blown outwardly, at the lower part inwardly, while 
midway, it will remain perpendicular. 

66. Argand lamps, or lamps which have a circular hollow wick surrounded 
with a glass cylinder, are supplied with a current of fresh air to support 
combustion by the same principle as the draft of a fire place. The heat of 
the flame expands the air above it, and this being thus rendered lighter than 
the atmosphere around, rises and leaves a vacuum towards which the sur- 



62. Exp. 3d. 

63. Exp. 4th. Why soft solids cool more slowly than liquids. 

64. Aeriform bodies in respect to their conducting power. 

65. What produces currents of air. 

66. Argand lamps. 



28 HEAT. 

rounding portions of air now press. The glass chimney becoming heated, 
serves still more to rarefy the enclosed air, and by thus rendering the up- 
ward current more lively, promotes combustion ; for with new portions of 
air, to supply the place of that which has ascended, fresh quantities of oxygen 
are added, and the flame is increased. 

67. When a fire is made in the open air, winds from all quar- 
ters are rushing towards it, even in the calmest day. This is 
because the air near the fire, being made lighter by heat, rises 
into higher regions of the atmosphere, and colder air rushes in 
to fill the vacuum. The heat of the sun over the tropical regions 
produces, by the expansion of air, the trade winds. 

68. The ventilation of rooms designed for large assemblies is 
effected by means of a dome, having an aperture at its vertex, 
under which is suspended a chandelier to heat the air and cause 
a draught. The cold air being constantly admitted below, to 
supply the place of the heated and vitiated air which ascends, a 
free current is kept up. 

Radiation and reflection of Caloric. 

69. All bodies are constantly giving out caloric ; and the tem- 
perature of a body rises, when it receives more than it gives 
out ; or falls, when it gives out more than it receives. The 
caloric thus given out, is called radiant caloric, and following 
the same law as light, emanates equally from all sides of the 
heated body, and proceeds in straight lines, moving with great 
velocity. By suspending a heated ball, and holding the hand 
at a short distance on any side, the heat will be immediately 
perceived, and, in the same degree in all directions. In this 
case, caloric is radiated, as it is from the Sun. 

70. Radiant caloric is reflected by various bodies ; and the laws 
which govern this reflection are the same as those which gov- 
ern the reflection of light. 

71. When a ray of heat falls obliquely upon a surface whether 
plane or curved, its direction is altered ; and the divergence is 
such, that, if we draw a perpendicular to the surface through 
the point where the ray strikes it, the angle between this perpen- 
dicular and the incident ray, is precisely equal to that between 
the same perpendicular and the reflected ray : in other words, 
the angle of incidence is equal to the angle of reflection. 

72. Exp. 1st. Resting one edge of a sheet of tin upon the hearth, incline 

67. Why wind blows towards a fire made in the open air. Cause of trade 
winds. 

68. Ventilation of public rooms. 

69. Radiant caloric. 

70. Reflection of radiant caloric. 

71. Law which governs the reflection of heat. 



RADIATION AND REFLECTION OF CALORIC. 



29 



it backward, till, on holding your face vertically over it, the image of the 
fire can be seen in the tin ; the warmth will be felt upon the face, though 
it be screened from the direct heat of the fire. 

Fig. 16. 





73. Exp. 2nd. Place a heated iron ball in the focus of a concave metallic 
mirror, (Fig. 16,) opposite to this, and at any convenient distance, place a 
second concave mirror, in the focus of which put a candle, having on its 
wick a bit of phosphorus. The diverging rays of radiant caloric proceeding 
from the ball to the mirror a, are reflected by the latter in parallel lines to 
the mirror b which converges them at its focus, igniting the phosphorus and 
thus lighting the candle. If a thermometer be substituted for the candle, 
the mercury in it will be raised by the radiated heat. 

74. Exp. 3d. Remove the heated ball from the focus of the mirror a 
(Fig. 16,) and replace it by a piece of ice; a thermometer in the focus of 
the mirror b, now radiates more caloric than it receives, and the mercury 
will instantly fall. This experiment has given rise to a supposition that a 
fluid of cold existed, and was radiated by the ice ; but cold is a mere negation, 
implying only the absence of heat. 

75. Exp. 4th. Sir Humphrey Davy contrived the following mode of 
showing the radiation of caloric. He placed 
two mirrors vertically, (Fig. 17,) with a wire- 
basket of burning charcoal in the focus of the 
upper one, and a little dish of phosphorus in 
the focus of the lower. The phosphorus was 
set on fire by the reflected heat from the lower 
mirror. Now all the heat that reaches this 
mirror, and is concentrated in its focus, must 
be radiant and reflected, as the current of 
heated air passes upwards. 

76. Bodies vary in their powers of 
radiating, and of reflecting caloric ; and 
these two properties are in an inverse 
proportion to each other ; that is, those 
substances which are the best radiators, ._,___, 
are, generally, the worst reflectors : or, as 
the radiating- power increases, the re- 
flecting power diminishes. 

72. Exp. 1st. 

73. Exp. 2nd. 

74. Exp. 3d. 

75. Exp. 4th. 

76. Reflection and radiation opposite qualities. 

3* 





Examples : the metals. 



30 



HEAT. 



Polished surfaces reflect caloric better than rough ones ; and 
the reflecting power of the same surface is directly in proportion 
to its degree of polish. Of all bodies, the metals when polished, 
are the best reflectors ; hence, they are used for mirrors, and 
for vessels to contain hot liquids as tea, coffee, &c. The heat 
which would be radiated from an earthen, or an unpolished ves- 
sel, is reflected back by a polished metal to the liquid ; hence, 
also the reason why polished andirons, &c. continue cool though 
exposed to the fire. Some of the metals are much better re- 
flectors than others ; and some alloys, or compounds of different 
metals, are better than pure metals : brass, an alloy of copper 
and zinc, is an excellent reflector. 

77. It is obvious, that the reflection of caloric must be directly 
opposed to absorption ; and, since it is equally obvious that the 
more caloric a body absorbs, the more it will radiate, the reason 
is manifest, why the best reflectors are the worst radiators. 

Fig. 18. 

a 




78. The differential thermometer is found to be very useful 
in experiments upon radiant heat ; as, when one of the bulbs is 
exposed to a higher temperature than the other, the difference 
between them is instantly shown, by the falling of the colored 
fluid below that which is most heated. 

Exp. 1st. Suppose a highly polished metallic mirror (Fig. 18,) a, placed 
a few feet from a cubical tin vessel b, filled with boiling water ; let a dif- 
ferential thermometer be placed so that one of the bulbs shall be in the fo- 
cus of the mirror, and an instantaneous rise of the temperature will be in- 



77, Why are the best reflectors, the worst radiators. 



ABSORPTION OF CALORIC. 31 

cheated by the instrument. If a glass mirror be substituted for the metallic 
one, the thermometer will be much less affected, by which it appears that 
glass is not so good a reflector of heat as polished metal. If the surface of 
the reflector be coated with lamp-black, all reflection is destroyed, and of 
course the thermometer is not affected. If a screen c, be interposed be- 
tween the tin vessel of hot water and thermometer, the latter will imme- 
diately indicate the absence of a portion of heat it before received, though 
the source of the heat is as near the bulb as before ; this shows that the 
thermometer was not affected merely by contiguity to the heated body, but 
by radiated heat. 

79. Exp. 2nd. If a cubical tin vessel, having one of its sides coated with 
lamp-black, another papered, and another glazed, be filled with boiling 
water, and the thermometer placed in the focus of a metallic reflector, it 
will be found, that as the different sides are respectively presented to the 
reflector, the thermometer will exhibit different degrees of temperature, 
showing that the different sides of the vessel possess the power of radiating 
heat in different degrees. 

The radiating power of lamp-black is found to be 100°. 



paper, 


98° 


glass, 


90° 


bright tin. 


12« 



80. Those bodies which absorb heat most readily, radiate it, 
most powerfully, that is absorbing and radiating powers are 
equal ; a piece of iron heats soon, and parts with its heat readi- 
ly ; a brick neither heats as soon, nor so quickly parts with ca- 
loric. 

It was formerly supposed that such substances as received heat most 
readily, must retain it longest ; philosophers, therefore, thought that 
housekeepers should make their tea in earthen or porcelain tea-pots, rather 
than in metallic ones ; but tea-makers insisted that they found by experience, 
that tea would " draw best" in bright silver or pewter tea-pots. The latter 
opinion is now proved by philosophy to be correct, since water retains its 
heat much longer in the polished metallic vessel, and, by this means, extracts 
more fully the peculiar virtues of the tea. 

81. Some colors absorb caloric more readily than others. This may be 
shown by a very simple experiment. Take a piece of black and another of 
white woolen cloth, and lay them upon the snow, when the sun is shining. 
In a few hours the black will be found to have sunk considerably below the 
surface of the snow, while the white will remain on the surface. From 
this we infer that the black cloth absorbed caloric from the sun, and gave it 
off in sufficient quantity to melt the snow beneath, while the white did not 
absorb, and consequently did not give off caloric ; with respect to light, 

78. Use of the differential thermometer in experiments upon radiant heat. 
Suppose a glass mirror be substituted for the metallic one, or the thermome- 
ter coated with lamp-black. How is it proved that the thermometer was not 
affected by contiguity to the heated body ? 

79. Exp. 2nd. Illustrating by means of the differential thermometer the 
radiating powers of lamp-black, paper, glass and tin. 

80. Absorption, and radiation equal. Why metallic tea-pots are better 
than earthen. 

81. Different powers of colors to absorb caloric. 



32 HEAT. 

black bodies absorb all the rays and reflect none ; while, in the case of ca- 
loric, black bodies not only absorb, but reflect in an equal proportion. Thus 
a white beaver hat is cooler for the head, in summer, than a black one, and 
light colored garments are more agreeable than dark colored. 

82. It is by contact with the earth, that the atmosphere be- 
comes hot ; for radiant caloric, either from the sun, or other 
sources, passes through aeriform bodies, without heating them. 
We, therefore, find the upper regions of the air, though nearer 
the source of heat, considerably colder than those next the 
earth. 

The formation of dew, is connected with this subject. In 
perfectly clear weather, the earth, which is, at all times radiat- 
ing caloric, cools rapidly as soon as the sun sets, for it then 
radiates more than it receives. The atmosphere contains watery 
vapor, which losing caloric by contiguity to the cool surface 
of the earth, becomes condensed and appears in drops, or minute 
particles of moisture, upon the leaves, flowers, and grass. 

Insensible Heat. 

83. If we immerse two thsrmometers in two portions of water 
just taken from the same reservoir, the temperature of each 
will he the same, however unequal their quantities ; yet it is 
evident that a quart of water must contain twice as much caloric 
as a pint of the same temperature. It is clear then, that the 
thermometer cannot indicate the absolute quantities of caloric 
contained in bodies ; and that every substance contains some 
heat, (the quantity being peculiar to itself,) which is not percep- 
tible by the senses, and does not affect the thermometer. This 
is called by the name of combined, insensible, or latent caloric. 

84. If equal portions of water, at different temperatures, be mixed, the 
temperature of the mixture will be found an exact arithmetical mean be- 
tween the two original temperatures ; but if equal weights of water, and any 
other liquid be mingled, under the same circumstances, the resulting tem- 
perature will differ from the mean. 

Exp. Mix a pound of water at 40°, with a pound of mercury at 185°, the 
thermometer will stand at only 45° in the mixture*, or if the water be at 
185°, and the mercury at 40° the mixture will raise the thermometer to 
180°. Here, in the first case, the 140° of caloric lost by the mercury, only 
increased the temperature of the water by 5°, and in the second case the 
water by losing 5° of heat, raised the mercury by 140°. 

85. The power that a body has of retaining more or less 
caloric in a latent state, is called in relation to another body its 

82. Heat of the atmosphere, how produced. Formation of dew. 

83. The thermometer does not indicate the absolute quantity of caloric in 
bodies. Name given to the portion of caloric that does not affect the ther- 
mometer. 

84. Effect of mixing water of different temperatures, or of mixing water 
and any other liquid. 



CALORIMETER. 33 

• dative capacity for caloric ; and the relative quantity of heat so 
retained, is called its specific caloric. Dr. Black, to whom the 
discovery of this difference of bodies in their relations to heat 
is due, supposes that the insensible caloric is in a state of chemi- 
cal combination, by which its properties are neutralized. 

The specific heat of bodies is estimated by comparing them 
with some particular body, of which, the specific heat has been 
taken as unity ; that of water is the standard which has been 
generally chosen. 

The experiment may be made by mixing them separately, with equal 
weights of water of a different temperature, and ascertaining the resulting 
temperature ; or by observing the time necessary to bring each to a given 
temperature by the same source of heat ; for those having the greatest spe- 
cific heat, (or capacity for caloric,) will require the longest time ; or, by 
observing their relative times of cooling under the same circumstances; for 
those which are longest in heating, are also longest in cooling ; or by ob- 
serving the quantity of ice which will be melted by each after having been 
heated to a given temperature ; for those having the greatest specific calo- 
ric, will melt the most ice. The last method is the foundation of Lavoi- 
sier's Calorimeter* 

86. In speaking of the specific heat of a particular body, we refer to that 
body in one state only ; for in passing from one state to another, it acquires 
a new specific caloric; thus, ice has a certain specific heat, water another, 
and steam another. Liquids have more specific heat than solids, and gases 
more than liquids ; the individuals of each class differing, also, among 
themselves. It is by absorbing and rendering latent, a quantity of caloric, 
that bodies pass from the solid to the liquid, and from the liquid to the 
gaseous state ; and when \apors are reconverted to liquids, and liquids to 
solids, the latent caloric becomes sensible. 

87. Laws of specific heat. 1st. Every substance has its 
particular specific caloric, which changes, when the body 
changes its form, or composition. 

2nd. Gaseous bodies, in becoming denser, lose, and in rarefy- 
ing, acquire capacity for caloric ; hence, 

3d. A change of density always occasions a change of tem- 
perature. 

The coldness of the upper regions of air, with the consequent 
presence of snow and ice on high mountain tops, is supposed to 
be caused by the rarity of the air at that height, by means of 
which it has a great capacity for heat, absorbs, and renders 
latent the free caloric from surrounding bodies, and, thus, re- 
mains, always, at a low temperature. 

* Calorimeter is from color, heat, and metron, measure, a measurer of heat. 

85. Meaning of the terms capacities for caloric, specific heat &c. Opin- 
ion of Dr. Black. Mode of estimating the specific heat of bodies. Exp. 
for ascertaining the specific heat of different bodies. 

86. Specific heat varies with change of state. 

87. Laws of specific heat. Cause of the coldness of the upper regions of 
the air. 



S4f HEAT. 



Liquefaction. 

88. Liquefaction is an effect of insensible caloric. If ice be 
moderately exposed to heat, it will gradually liquefy, and the 
temperature will be at 32°, during the whole process of melting ; 
but the last portion of ice being dissolved, the water will gradu- 
ally grow warm, till it attains the temperature of the surround- 
ing atmosphere. Here the ice has been receiving caloric which 
has had no sensible effect in raising its temperature, but has 
been occupied in bringing it to the liquid state. This latent heat 
in the water, is called the caloric of fluidity. The same process 
takes place, whenever any solid becomes liquid, as in the dis- 
solving of saline bodies, the fusion of metals, &c. When a metal 
is heated to a certain degree, called its fusing point, a portion 
of it begins to melt ; all the heat received after this, goes to 
carry on the process of liquefaction ; the temperature remaining 
stationary, till all the metal is in a state of fusion ; after which, 
if the heat be continued the temperature will increase. 

89. The heat which has been appropriated in these instances, 
is always given out again, when the liquid becomes solid ; for 
example ; if water be kept entirely motionless, it may be cooled 
by artificial means, several degrees below the freezing point, 
(32° ;) but on agitating it, a portion freezes, and in solidifying, 
gives out sufficient caloric to raise the whole to 32°. Sulphur 
and phosphorus, after having been fused, may sometimes 
be cooled to common temperatures without resuming their 
solidity ; but if in this state, they are touched with a glass rod 
or other substance, they instantly solidify, giving out their 
caloric of fluidity. 

The principle deduced from the fact that caloric disappears during 
the liquefaction of a solid, is usefully applied to the obtaining very 
low temperatures, artificially, by means of freezing mixtures. 

90. Frigorific,* or freezing Mixtures, consist, of certain soluble salts, and 
snow, or pounded ice. The effect depends on the tendency of the salt to 
dissolve in water ; this induces the liquefaction of the ice, by which, heat 
is absorbed; and the salt dissolving in the water thus formed, removes a 
further portion of heat. It is obvious that the more rapid the liquefaction, 
the more intense the cold produced, and therefore the most effective ; the 

* From frigus cold, and facio to make. 

88. Caloric of fluidity. 

89. What becomes of the caloric of fluidity, when the liquid is reconverted 
to a solid. 

90. Of what freezing mixtures consist, and how prepared. Greatest cold 
produced. 



FREEZING MIXTURES. 



35 



pulverizing of the materials assists the operation, by hastening the process 
of solution. By the use of equal weights of crystalized muriate of lime and 
snow, quicksilver has been frozen. The greatest cold produced by freezing 
mixtures, is said to be about 100° below the zero of Fahrenheit; by evap- 
oration, a mere intense cold may be produced, but no known process can 
deprive a body of all its caloric. 

91. In employing these mixtures, care must be taken that they are 
thoroughly mingled together. The best vessels for using them, are of metallic 
ores of different sizes, having double sides at a distance of half an inch 
from each other. The article to be frozen, is to be put into the smaller 
vessel, which may then be placed in a larger one, and surrounded with the 
mixture. A double cover is now to be put on, to prevent the caloric of the 
atmosphere from defeating the experiment. 

In making ice cream, the vessel (Fig. 19.) used for contain- (Fig. 19.) 
ing the mixture to be frozen, is usually of tin, and of the form 
represented in the figure ; a is the body of the vessel, and b the£ 
handle affixed to the cover, which is made to fit very close to 
exclude the caloric of the atmosphere. The cream, now being 
prepared with sugar, &c, is put into the tin vessel, which is 
then immersed in pounded ice and salt, or other freezing 
mixture, contained in a larger vessel. To facilitate the freez- 
ing process, the vessel containing the cream must be occa- 
sionally shaken by the handle. When the cream is found to a j 
be frozen around the side of the vessel, which is in contact 
with the freezing mixture, a knife or spoon should be intro- 
duced to remove the frozen parts, so that other portions may take its place. 




Freezing Mixtures. 



Mixtures. pts. 

Sea salt 
Snow 
Sea salt 

Muriate of ammonia 
Snow 
Sea salt 

Nitrate of ammonia 
Snow 

Dilute Sulphuric acid 
Snow 

Concentrated Muriatic acid 
Snow 

Concentrated Nitrous acid 
Snow 

Chloride of Calcium 
Snow 

Fused potassa 
Snow 



by wt. 
1 

2 
2 
1 
5 
5 
5 

12 
2 
3 
5 
8 
4 
7 
5 
4 



Thermometer sinks. 
to — 5° 



to — 12° 



to —25° 



t\ 



from + 32° to — 27° 

— +32° to — 30° 
h 32° to — 40° 

— + 32° to — 51° 



I from + 32° to — 23° I 

\ 

\ 



Degree of 

cold 
produced. 



550 
59» 
62° 
72° 
83° 



91. Manner of using these mixtures. Ice cream apparatus. 



VAPORIZATION. 



Freezing is also effected by the rapid solution of Salts. 

Mixtures. pts. by wt. Thermometer falls. 
Muriate of ammonia 5 

Nitrate of potassa 5 } from + 50° to -f 10° 40° 

Water 10 



Nitrate of ammonia 

Water 

Nitrate of ammonia 

Carbonate of Soda 

Water 



I — + 50° to -|- 4° 



46° 



— + 50° to -f 70 } 570 



?S P ? a i e *# S ° da 'A l\ from 4- 50o to -30 530 

Diluted .Nitrous acid 2 ^ ' J> 

Sulphate of Soda 6 ) ) 

Nitrate of ammonia 5 V —4- 50° to— 14° V 64° 

Diluted Nitrous acid 4 ) ) 

Phosphate of Soda 9 > _ __ ^ j 

Diluted Nitrous acid 4 $ $ 

Phosphate of Soda 

Nitrate of ammonia 6} f- 50° to — 21° 71° 



Diluted Nitrous acid 4 

Katfcir 5 I f-n+ 50o,„ -00 

MSXttaeid 4 I <•- + 50O,„ + 30 \ 47» 

To produce the greatest effect, the substances should be cooled in a freez- 
ing mixture before they are united. 



CHAPTER IV. 

VAPORIZATION. EBULLITION. STEAM DISTILLATION. GASES AND 

VAPORS. 

Vaporization. 

92. Vaporization is the conversion of liquid and solid sub- 
stances into vapor, which may be effected in two ways ; viz 5 by 
evaporation and ebullition ; the former takes place without any 
visible motion among the particles, while the latter is manifested 
by external agitation. 

93. Such bodies as have never been converted into vapor by 
heat, are said to be fixed; substances known to be vaporizable, are 
called volatile. Solids usually become liquids before they va- 
porize ; some, however, as arsenic and iodine, pass at once from 
the solid, to the aeriform state. 

92. Vaporization. How produced. 

93. Fixed and volatile bodies. 



VAPORIZATION. 37 

94. Evaporation is the slow conversion of a body into vapor. 
It takes place whenever a liquid is exposed freely to air. In a 
very few cases, also, solids disappear, slowly, from the same 
cause. 

A vapor differs from a gas in being more easily condensed into a liquid ; 
the drying of wet clothes in the air, is an example; and sometimes the vapor 
may be seen rising and passing off. If such clothes are exposed to a fresh 
and keen wind, with the air some degrees above the freezing point, the 
current of air hastens the process of evaporation, and heat is so rapidly 
carried off, as to cause the freezing of the remaining water, and the cloth 
is hard and stiff, until further evaporation carries off all the water contained 
within its pores. 

95. The. rapidity of evaporation is influenced by the following 
circumstances. 

1st. By the form of the vessel ; the evaporation takes place 
only from the exposed surface. A liquid to be evaporated, 
should, therefore, be put into a shallow vessel. 

2nd. By the moisture or dryness of the air. The atmosphere 
is capable of retaining only a certain quantity of vapor ; the dry- 
er the air, therefore, the more rapid the evaporation. 

3d. By the motion or stillness of the air. Evaporation takes 
place more rapidly when there are currents, by means of which, 
the saturated air is constantly removed and replaced by dry por- 
tions. 

4th. By pressure on the surface. If any liquid be placed under 
the exhausted receiver of an air pump, the pressure of the at- 
mosphere being now removed, the evaporation will take place 
with much greater rapidity. 

96. Observe, that in a short time, the receiver would become filled with 
an atmosphere of vapor, which would exert a pressure as the atmosphere 
did before, and retard evaporation. But, if we place under the receiver 
some substance capable of absorbing the vapor as fast as it forms, the va- 
cuum will be kept up, and the evaporation will continue as rapid as before. 
It is found that sulphuric acid has a powerful attraction for watery vapor. 
Professor Leslie has shown that by placing water in a fiat dish over this 
acid, and removing the atmospheric pressure by an air pump, the rapid 
evaporation which takes place, renders latent so much of the caloric of the 
water, that a portion of it will freeze. 

Exp. Upon the plate of an air pump, (Fig 20) place a flat, shallow, glass 
dish, A, about half filled with sulphuric acid, and a little above it, a tin or 
copper basin B, three parts filled with water, and a small thermometer C, 
immersed in the liquid. 

This basin, is supported upon three glass legs, D, standing in the acid, 
and an air-pump receiver is placed over it. On proceeding to exhaust the 
air, the thermometer gradually sinks ; the water, in consequence of the ra- 
pidity of its evaporation, appears to boil, and if the apparatus is in good order, 
it freezes in the course of five or ten minutes. The use of the surface of 

94. Evaporation. Example. 

95. Circumstances which influence the rapidity of evaporation. 

4 



38 



EVAPORATION. 
Fig. 20. 




Fig. 21. 



sulphuric acid here, is to absorb the aqueous vapor, which it does very 
energetically, and consequently occasions a constant call upon the water 
for its formation. Now, vapor cannot beproduccd without the absorption of heat ; 
and in the case before us, the heat requisite to convert one part of the water 
into vapor, is taken from the other fluid portion, which, thus losing the heat 
that constituted its fluidity, becomes solid, or freezes. There is another 
phenomenon often observable in this experiment, which is, that the tem- 
perature of the water falls several degrees below the freezing point, before 
congelation takes place ; but the moment that the water freezes, it rises to 
32°, in consequence of the escape of the residuary latent heat." 

97. By the evaporation of ether, under an exhausted receiver, water may 
also be frozen. 

Suppose a thin glass flask (Fig. 21) contain- 
ing a portion of ether, is placed in a wine 
glass containing cold water to the level at a, 
and then covered with the receiver of an air- 
pump. On exhausting the air, the ether will 
pass into a state of vapor. In evaporating, 
the ether takes caloric from the surrounding 
bodies ; the water in contact with it loses its 
caloric of fluidity, and becomes solid. A small 
animal, if exposed to a current of air, while 
wet with ether, would soon die from privation 
of vital heat. 

98. Dr. Wollaston's Cryophorus, (Fig. 22,) 
or Frost-bearer consists of a tube with a bulb, 
a, and b, at each end. One of the bulbs, b, is 

I s '■ — *v partly filled with water, and the remaining 

space contains watery vapor ; the atmospheric air having been expelled by 
boiling the liquid, as in making a thermometer. If now the bulb, a, is 
immersed in a freezing mixture, the watery vapor will be condensed by 




96. Use of sulphuric acid in evaporating water by the pressure of the at- 
mosphere. Prof. Leslie's experiment 

97. Water frozen by the evaporation of ether. 

98. Cryophorus. 



EVAPORATION. 
Fig. 22. 



39 





cold ; a vacuum being formed, a new portion of vapor will rise from the 
water in the other bulb, and, in its turn, be condensed ; in a few minutes, 
the water in the bulb at 6, will be frozen quite solid. 

The bulb may be secured against the admission of caloric, by a covered 
glass, as in the figure at b. 

Fig. 23. 99. The pulse glass (Fig. 23.) 

is a small instrument resembling 
in its form the cryophorus. It 
contains a small portion of alco- 
hol, and highly rarefied air. On 
grasping with the warm hand, 
the bulb which contains the liquid, an ebullition takes place ; the alcohol is 
converted into vapor, and passes over into the other bulb. The hand ex- 
periences a sensation of intense cold, on account of the heat which passes 
from it into the alcohol. The sensible heat of the hand has become latent 
heat in the newly formed vapor, which, if tested by the thermometer, would 
exhibit no increase of temperature above that of the liquid from which it 
had been formed. 

100. Of all the causes which produce evaporation, temperature is the 
most effective. 

101. The effect of heat in promoting evaporation, is extensively useful 
in chemical operations. It is often necessary to remove a portion, or the 
whole of a liquid, when it can be done in no other way than by evaporation ; 
and this is usually effected by placing the liquid, contained in a flat dish, on 
a bed of sand, heated by a furnace below. This is called a sand-bath, and 
facilitates the regulation and equal distribution of heat. When evaporation 
is thus accelerated by heat, the vapor forms more or less rapidly, till 
the temperature is raised to a certain point, when the portions of the 
liquid in contact with the heated vessel, are converted into vapor, which 
forcing its way through the liquid, rises, in bubbles, to the surface, and 
escapes. 



99. Pulse glass. 

100. Effect of temperature on evaporation. 

101. Utility of evapo'ation in chemical operations. Sand-bath. Effect 
of hastening evaporation by heat. 



40 HEAT. 

Ebullition. 

102. The agitation of a liquid occasioned by a rapid escape 
of vapor is called ebullition or boiling ; it is usually attended with 
some degree of sound. If a portion of water be placed in a glass 
flask, closely corked and subjected to the heat of a lamp, the 
water will soon begin to boil, and its quantity will gradually 
diminish, until the vessel will seem to be empty. But as it will 
be found to have the same weight as before the water boiled, 
it can have lost nothing. Expose this vessel to the cold air ; 
moisture will begin to collect upon the inner side of the glass, 
until the same quantity of water, as the vessel at first contained, 
will appear at the bottom ; this water will exhibit the same 
properties as before evaporation. 

103. Dr. Black instituted some ingenious experiments, to determine the 
actual loss of heat during the conversion of water into steam. He heated 
water in a tin vessel up to the boiling point, and noted the time required 
for the purpose. The same heat was then continued, till the whole of the 
water was evaporated ; and the time taken up by that process was also 
noted. Now since, on the one hand the accession of heat was constant, it 
was easily computed how high the temperature could have been, supposing 
the rise to have gone on above 212°, in the same ratio, as below it ; and, 
on the other, as the temperature of the steam was not raised, it was inferred 
that all the accession of heat from 212°, was essential to the very state and 
constitution of steam at that temperature ; this quantity was estimated at 
about 810° ; that is to say, that the same quantity of heat which is required 
totally to evapoi'ate boiling water at 212°, would be sufficient to raise the 
water 810°, above the boiling point, or to 1022° if it had remained in the 
liquid state. 

104. When steam is condensed into water, it gives out the 
latent heat which was essential to its state of vapor, and which, 
when set free, will raise the temperature of adjacent bodies, as 
much more than an equal weight of boiling water would do, as 
the latent heat of steam exceeds that of boiling water. 

105. A small steam-boiler (Fig. 24,) a has been contrived for experiments 
on latent heat. The boiler is furnished with two stop cocks, b and rf, to the 
latter of which is screwed the pipe e ; when the latent heat of vapor is to 
be determined, water is put into the boiler, and made to boil by the appli- 
cation of an Argand lamp / ; the end of the pipe c, being immersed in a 
given quantity of water in the vessel g, furnished with a thermometer h. 
After the water has boiled for some time, the increase of weight of the 
water in the vessel g may be ascertained, and then the indication of the 
thermometer will show how much heat has been imparted to the water by 

102. Cause of ebullition. Change which water undergoes in boiling. 
How is it proved that water loses nothing, and suffers no change in its 
constitution by boiling ? 

103. Inferences drawn from Dr. Black's experiments upon the heat 
required for converting water into steam. 

104. Heat given out when steam is condensed into water. 

105. Apparatus for experiments on latent heat, mode of using it, with 
inferences from the changes which are observed. 




the condensation of a quantity of steam equal to the increase of weight. 
The effect thus produced may be compared with that which would result 
from the addition of an equal weight of boiling water ; and it will be found 
that a given weight of steam at 212°, has the power of heating water many 
times more than an equal weight of water at the same temperature. The 
thermometer c passes through a collar into the boiler a for the purpose of 
ascertaining the heat of its contents. 

106. It is probably, the greater affinity of heat for steam, 
more than for water, that makes the boiling point of water so 
perfectly stationary in open vessels over the strongest fires. 

Every kind of liquid has its own particular temperature, at 
which it boils, called the boiling point. Beyond this point, no 
liquid can be heated in the open air ; all the heat afterwards 
acquired, being consumed in converting the liquid into vapor ; 
and every vapor, at the time of its being evolved, has the same 
temperature with the liquid which yielded it. Thus, water, as 
we have seen, cannot be heated under ordinary circumstances, 
and in open vessels, to a higher temperature than 212°, and the 
steam which rises is also at 212°. Alcohol boils at 173°, and 
ether at 96°. 

107. The boiling point of water, may be made to vary with 



106. "Why the boiling point of water is stationary in open vessels, with 
different degrees of heat. Meaning of the expression, " boiling point." 
Boiling point of water, alcohol, and ether. 

107. Circumstances which cause the boiling point of liquids to vary. 

4* 



4>2 HEAT. 

circumstances. 1st. The nature of- the vessel used has some in- 
fluence ; the boiling point of water rises to 214° in a glass vessel, 
while it boils at 212° in one of iron. 2nd. The introduction of 
iron filings causes water, boiling at 214>° in a glass vessel, to 
yield steam at 212°. 

This expedient is often used to facilitate the ebullition of liquids, which 
have a high boiling point : thus, sulphuric acid, which boils with violent 
jerks at 620°, is made to yield its vapor steadily, and quietly, by introducing 
a crumpled piece of platinum-foil. The substance added, however, must 
be such as has no chemical action on the liquids. 

3d. Pressure has the greatest influence on the boiling point 
of liquids. The weight of the atmosphere (15 lbs. upon every 
square inch,) is the only obstacle which prevents many liquids 
from existing as vapors, at ordinary temperatures. Thus, ether 
and alcohol boil at the common temperature, under the exhausted 
receiver of the air pump, and water will boil, in a vacuum, at a 
temperature of 72°. 

108. If water, heated to the boiling jpoint, be withdrawn from 
the fire, the boiling will cease ; if the vessel containing the water 
be placed under the receiver of an air pump and the air exhausted, 
ebullition will again take place, and will continue, till the tem- 
perature of the water has fallen below 72°. 

109. It has been shown that atmospheric pressure raises the boiling 
points of all liquids 140°, higher than the temperature at which they boil 
in a vacuum. When the boiling point of a liquid is stated, it is to be 
understood that the barometer stood during the experiment, at the medium 
height, or 30 inches. If the mercurial column be higher than that, the 
boiling point will rise, if lower it will fall. The temperature at which 
watery, or other vapor, is able to overcome the atmospheric pressure and 
escape, may be used, instead of the height of the mercurial column, to 
ascertain the amount of that pressure ; and since the weight of the air de- 
creases in a constant ratio as we ascend, water will boil, more readily, on 
the top of a mountain, than on the plain below ; so that we may ascertain 
the height of the mountain, by observing the temperature at which water 
boils on its summit, allowing 530 feet for each degree of Fahrenheit's ther- 
mometer. 

110. The effect of diminished pressure may be satisfactorily shown as 
follows. 

Exp, Fit a stop-cock to the neck of a glass flask ; half fill the flask with 
water, and place it over the flames of a lamp, let it boil a few minutes, till 
the air is all expelled, and the steam escapes freely through the open stop- 
cock. On removing the lamp, and closing the stop-cock ; the ebullition 
will instantly cease. But if the flask be suddenly plunged into a vessel of 

108. Experiment to show that water boils with less heat when the 
pressure of the atmosphere is removed. 

109. What is the effect with respect to the boiling point of a liquid when 
the barometer is higher or lower than the medium height? Why does 
water boil with less heat upon high mountains than at their base ? 

110. Why does a flask of water stop boiling when exposed to a certain 
degree of heat, and re-commence boiling on being plunged into cold water? 



STEAM. 43 

cold water, the steam within the flask, which by pressing on the liquid 
prevented the formation of vapor, will be partially condensed, and the boil- 
ing will re-commence, and continue till a new atmosphere of steam is 
formed. This may be condensed by a second immersion in cold water, and 
so on, till the temperature of the water within the flask, is reduced below 
the boiling point. 

Steam. 

111. As the boiling point of liquids may be made lower by di- 
minution of pressure, so the contrary effect may be produced by 
an increase of it. If water be heated in a strong vessel, closed 
so that steam cannot make its escape, its temperature may be 
raised even to a red heat, without ebullition ; the only limit, 
being, the strength of the vessel to resist the immense expansive 
force of the liquid. If an aperture were suddenly made in the 
vessel, a large quantity of the water would flash at once into 
steam, with explosive violence. When water is heated in a 
common tea-kettle, if the lid fits closely, so that the steam when 
formed, cannot escape, the accumulation of vapor in the upper 
part of the kettle, will soon cause an increased pressure on the 
surface of the water below, forcing a portion of it out at the 
spout ; when the steam has thus made room for itself, or if the 
lid be removed, the spouting jet will cease. 

112. Steam generated under pressure, at temperatures above 
the ordinary boiling point, is called high pressure steam j that 
formed in the usual manner under atmospheric pressure only, is 
called low pressure steam. 

113. All vapors can be condensed into liquids, by coming into 
contact with a cold surface, whereby a part of their latent heat 
is taken away ; or by subjecting them to pressure, in which case, 
also, they yield their caloric of expansion, and the vessels in 
which they are condensed become heated. 

114. Steam, as it issues from an escape-pipe, is transparent, 
and nearly invisible ; but it becomes opake at a very short dis- 
tance from the mouth of the pipe. This is caused by its being 
condensed by the cold air. 

115. Instruments invented to prevent the loss of heat by evaporation are 
called digesters. Papin's digester, is a cylindrical copper vessel, having a 
lid nicely fitted to it, and secured by screws. " If such a vessel be about 
half filled with water, with the lid closely secured, and then put upon the 
fire, steam is soon formed ; but having no escape, it presses upon the 

111. Effect of increased pressure upon the boiling of liquids and con- 
sequently, m retarding the formation of steam. 

112. High and low pressure steam. 

113. How may all vapors be condensed into liquids ? 

114. Transparency of pure steam. 

115. Digesters. Papin's digester. 



HEAT. 



water, and prevents the further formation of steam, till the temperature 
of the water rises above the boiling point. This heat being conveyed to 
the steam, it now receives another portion of vapor without being condensed, 
and thus the quantity and the elasticity of the steam, are continually in- 
creasing with the temperature. Water has in this way been raised to the 
temperature of 419°." 

116. At the temperature of 419°, the elasticity of steam is 
1050 times greater than that of atmospheric air ; so that it ex- 
erts, upon the inside of the vessel in which it is pent up, a force 
of at least 14700 pounds pressure on each square inch • a pressure 
so enormous that few vessels can resist it, and h ence have occurred 



Fig. 25. 




many serious accidents, which, in the 
applications, of high pressure steam, are 
now guarded against, by safety valves 
and other similar contrivances. 

117. Exp. (Fig. 25;) a is a strong brass globe, 
composed of two hemispheres screwed together ; 
a portion of quicksilver being introduced into it, 
it is about half filled with water ; b a barometer 
tube passing through a steam-tight collar, and 
dipping into the quicksilver at the bottom of the 
globe : c a thermometer graduated to about 400°, 
and also passing through an air-tight collar : d is 
a stop-cock, and e a large spirit-lamp. The 
whole is supported upon the brass frame and 
stand,/. Upon applying heat to this vessel, and 
closing the stop-cock as soon as the water boils, 
it will be found that the temperature both of the 
water and of its vapor, increases with the pres- 
sure, the extent of the latter being measured by 
the ascent of the mercury in the barometer. 
The thermometer, under an atmospheric pressure 
of 30 inches, being at 212°, will be elevated to 
221°, under an additional pressure of 5 inches*, 
and to 269°, under an additional pressure of 30 
inches, (or one additional atmosphere,) each inch 
of mercury, above 30, producing by its pressure, 
a rise of about 192°, in the thermometer. The 
barometer tube also serves the purpose of a safety 
valve, the strength of the brass globe being such 
as to resist a greater pressure than that of our 
atmosphere. 

118. The latent caloric of steam may 

r^^-be economically employed in heating 

""large rooms, by conveying it in pipes j 

and this expedient is sometimes used in 

manufactories of ether, and other inflam- 



116. Elastic force of steam. 

117. Apparatus for exhibiting the elastic force of steam. 

118. Economical applications of the latent heat of steam. 



STEAM. 



45 



mable articles, where fire would be unsafe. Water soon 
comes heated by a current of steam being condensed in it. 

Distillation. 



be- 



119. Distillation consists in converting substances into vapor, 
and condensing this into a liquid. 

The distilling apparatus consists of retorts, receivers, alembics and the 
still and worm. In using them, the receiver, or the head of the alembic, 
must be kept cool by ice, moistened cloths, or otherwise. On a large scale, 
as in distillation of ardent spirits, the still and worm are used, the latter 
consists of a long, spiral, metallic tube, set in a vessel of cold water ; the 
vapor being conveyed into this, condensed by passing over a great extent 
of cold surface. 

120. Exp. (fig. 26.) Into a glass 
alembic a put one part of spirit 
of wine, and seven or eight parts 
of colored water. Before put- 
ting the mixture into the alembic, 
plunge into it a burning paper, 
and the flame will be extinguish- 
ed. This will prove that the 
mixture is not inflammable. Ap- 
ply the heat of a spirit lamp 6, 
and the lower part of the ap- 
paratus will soon become dim 
with moisture ; a portion of the 
alcohol will be raised in vapor 
and coming into contact with 
the sides of the vessel, will at 
first be condensed ; but this ves- 
sel will very speedily become 
too hot to condense the vapor ; 
it will then ascend into the head 
of the alembic c, and being there condensed, will run down into the re- 
ceiver d } where, in a short time will appear a small quantity of pure, color- 
less liquid. If this be poured into an open vessel and a piece of burning 
paper applied, it will take fire and burn to dryness. Thus, it will be proved, 
that from a colored and uninflammable mixture, a pure, colorless, inflam- 
mable spirit has been obtained by distillation. 

121. The form of still most commonly used, is represented in fig. 27: a, 
is the furnace ; b, the capital, or head of the copper still ; c, part of the 
chimney ; d, the worm tub, containing cold water for condensing the vapor 
that enters the worm. The vapor, in passing through this cold, spiral, 
metallic tube, becomes condensed and liquefied, and passes from it, in its 
distilled form, into the vessel beneath. 




119. What is distillation ? How conducted ? 

120. Experiment to explain the changes in distillation. 

121. Explanation of Fig. 27. 




122. By the process of distillation, volatile bodies are sepa- 
rated from those that are more gross ; for example, by distilling 
salt water, we may obtain fresh water ; the saline matter, remain- 
ing In the retort. 

Gases and Vapors. 

123. Gases were long considered as permanently elastic 
fluids, differing essentially from vapors, which readily condense 
into liquids. But Mr. Faraday has succeeded, by means of in- 
tense artificial cold, and very great pressure united, in liquefy- 
ing many of the gases ; and it is now thought probable, that all 
of them are the vapors of liquids having boiling points very far 
below any natural temperature. The term gas, however, is still 
applied to those bodies which retain the aeriform state under 
ordinary atmospheric pressure and temperature. 

The different gases require very different degrees of pressure and reduc- 
tion of temperature for their liquefaction ; all of the liquids thus obtained, 
have so strong a tendency to resume their elastic state, that, on breaking 
the tube in which they are confined, they expand with great force, producing 
of course, intense cold, and frequently exploding, so as to endanger the 
operator. 

124. Vapors, so long as they remain uncondensed, have all 

122. Distillation of salt water. 

123. Distinction commonly made between gases and vapors. 

124. Properties of vapors which render them useful as a motive power. 
The steam engine. 



GASES AND VAPORS. 



47 



Fig. 28. 



the physical properties of gases. Their elasticity and condensi r 
bility render them useful as a motive power. The action of the 
steam engine depends chiefly upon two properties of steam ; 
viz. expansive force, and easy condensation. 

Let a, (Fig. 28) represent a glass tube with a 
bulb at its lower end. It is hefd in a brass ring 
to which a wooden handle, b is attached, and con- 
tains a piston, c, which, as well as its rod is per- 
forated, and may be opened or closed by the screw 
at top, d ; it is kept central by passing through a 
slice of cork at e. A little water being poured 
into the bulb, and carefully heated over a spirit 
lamp, the aperture in the piston being open, the 
air is expelled ; and when steam freely follows it, 
the screw may be closed. On applying cold to 
the bulb, the included steam is condensed, and a 
vacuum formed, which causes the descent of the 
piston, in consequence of the air pressing on it 
from above. On again holding the bulb over the 
lamp, steam is re-produced, and the piston again 
forced up, and these alternate motions may be 
repeatedly performed by the alternate applications 
of heat and cold. The ascent of the piston of a 
steam engine, is caused by the expansive force, or 
elasticity "of steam, forcing the piston upward. 

125. In former steam engines, the descending 
stroke was produced by injecting cold water, which 
condensed the steam and produced a partial va- 
cuum ; the atmospheric pressure then counter- 
balanced the force beneath the piston, and impelled 
it downward. Watt's great improvement in the steam engine consists in 
conveying off the steam after it has performed the office of raising the 
piston, and condensing it in a separate vessel; thus avoiding the great loss 
of heat, formerly incurred by cooling the cylinder at each stroke of the 
piston. 

126. Mr. Dalton has deduced from experiments, the interesting law, that 
the vapors of all liquids have the same elasticity at the same distance above, 
or below their respective boiling points ; thus the vapor of ether at 87°, 
has the same tension or elastic force as that of water at 202°, or that of 
alcohol at 163°, those temperatures being respectively ten degrees below 
the boiling points of the different liquids. From this, also, it results that 
the vapor of mercury at 60°, (the boiling point being 680°,) has a tension 
equal to that of water 620° below its boiling point ; that is, to that of water 
at 408° below zero ; which is so small that it could not overcome the 
pressure of atmosphere. It is, therefore, concluded that mercury and other 
liquids having very high points of ebullition do not evaporate at common 
temperatures. 




125. Manner in which the descending stroke of the steam piston was 
formerly produced. Watt*s improvement. 

126. Mr. Dalton's discovery of the law which governs the elasticity of 
vapors. Elastic force of the vapor of mercury at 60°. 



48 HEAT. 



CHAPTER V. 

LIGHT. DECOMPOSITION OF LIGHT. ILLUMINATING, HEATING, COLOR- 
ING, AND MAGNETIC RAYS. FLAME. PHOSPHORESCENCE. 

127. Light, considered as to its physical properties, belongs 
to the science of Optics, which is a branch of Natural Philosophy. 
But its chemical agencies bring it within the scope of Chemistry. 
Light is subject to radiation and reflection, in the same manner, 
and according to the same laws, as caloric ; the bodies which 
reflect the one, being also reflectors of the other. 

128. Light is the agent of vision, or of seeing. Rays of light 
thrown out from all the points of a luminous body, are collected 
by the lens of the eye, and thrown upon the retina, producing 
there the image of the radiating body. Objects, not of them- 
selves luminous, are seen by means of light thrown upon them 
from the sun or other sources, and reflected to the eye of the 
observer. 

129. The refraction of light takes place when a ray passes 
from a rarer, to a denser medium as from air to water ; this 
property is called refrangibility. It is the refraction of light, 
that causes a stick partly immersed in water to appear bent ; 
and tiie different densities of the warm air over a stove, and 
the colder air on each side of it, cause objects, seen through 
both, to appear distorted. Objects seen through some substances, 
as Iceland spar, appear double in consequence of a double 
refraction. 

130. Bodies which permit light to pass freely through them, 
are called transparent, those which do not, opake. A perfectly 
transparent body cannot reflect light, and therefore cannot be 
visible. Although the solar rays possess calorific or heating 
power, transparent bodies are not heated when light passes 
through them ; neither do reflectors of light absorb any of the 
caloric of the rays. For this reason, concave mirrors and burn- 
ing glasses remain cool themselves, though they concentrate 
and transmit light and heat, to an intense degree, upon bodies 
in their foci. 

131. It is remarkable that a close relation seems to exist be- 

127. Definition of light. Why has light a relation with both Natural 
Philosophy and Chemistry ? How does light resemble caloric ? 

128. Light the cause of vision. 

129. Refraction. Double refraction. 

130. Transparent and opake bodies. Why reflectors and lenses are 
not heated by the calorific rays which they reflect or transmit. 



LIGHT. 49 

tween the combustible and refracting powers of substances ; the 
most combustible, being also the most refractive, provided they 
be at the same time transparent. Hydrogen, the most power- 
fully combustible of the gases, has the highest refracting power; 
oxygen, the most eminent supporter of combustion, is the most 
feeble refractor of light. The diamond, and water were pro- 
nounced by Newton to contain combustibles, long before their 
chemical nature was known. 

132. The light of the sun and stars contains, 1st. Colorific, or 
illuminating rays. 2nd. Calorific, or heating rays. 3d. Chemi- 
cal rays, or those which produce chemical effects. 

133. Colorific rays, A ray of solar light received on a 
transparent, triangular prism of glass or other transparent sub- 
stance, is found, after its passage, to be resolved into seven rays 
or colors \ their separation being caused by the different re- 
frangibility of the rays. The colored image is called the solar 
spectrum. The phenomenon of the rainbow is produced by the 
decomposition of light in passing through drops of rain. New- 
ton was led to discover this, by observing that drops of rain 
exhibited a variety of colors when the sun shone upon them, 
and also that the arrangement of the colors of the rainbow was 
always the same. 

134. Certain bodies have the property of decomposing the light given out 
by substances burning in contact with them, and of yielding only one 
colored ray. 

Exp. Moisten table salt with alcohol, and set it on fire in a dark room ; 
the flame contains only the yellow ray, and the human face seen by its 
light, has a ghastly hue, while a red handkerchief, or anything not capable 
of reflecting the yellow ray, appears black. Borax,* gives a green, and 
the salts of strontia a red tinge to the flame of alcohol. These effects 
are attributed to a decomposition of the rays of light by the salt, all the 
primary colors being absorbed, except that which is visible in the flame. 
Such lights are ealled monochromatic]. 

Every variety of color can be produced by the action of chemical agents 
upon each other. 

Exp. Red and indigo form violet. 

Exp. Red vegetable infusion and an alkali, green. 

Exp. The above infusion with an acid, red. 

Exp. Into chloride of calcium pour sulphuric acid and a white solid 
will be formed. 

* A salt comprised of boracic acid and soda, 
f From the Greek monos, one, and chroma, color. 



131. Connection between the combustible and refracting powers of 
substances. 

132. Three kinds of rays of light. 

133. Solar spectrum. Cause of the rain-bow. 

134. Exp. With table salt and alcohol, borax and strontia. Cause of 
these effects. 

5 



50 ILLUMINATING POWER. 

Exp. To a dilute solution of persulphate of iron, pour tincture of nut- 
galls, and black ink will appear. 

Exp. Sulphate of iron with terro-cyanuret of potassa forms indigo. 
Exp. Sulphate of copper and aqua ammonia form blue. 

135. The illuminating power of the different rays is by no 
means equal, the greatest being- in the yellow and green, less in 
the blue and red, still less in the indigo, and comparatively little 
in the violet. This explains the familiar fact, that a room of 
which the walls are yellow or pale green, is much more easily 
lighted, than one painted blue, or any other color. 

136. Calorific rays. The heating power of the colored rays 
is greatest in the red, and least in the violet ; but it is found 
that there are invisible rays, beyond the red, (and, therefore, 
less refrangible rays,) in which is contained the greatest heat of 
the spectrum. It had been supposed by philosophers, that the 
heating power in the spectrum would be proportioned to the 
quantity of light, and therefore the yellow was accounted the 
warmest of the colored rays. But Dr. Herschel, by a series 
of experiments, proved that the heating power gradually in- 
creased from the violet ray to the red. He ascertained, more- 
over, that the thermometer continued to rise when placed beyond 
the red extremity of the spectrum, where not a single ray of 
light was seen. From these phenomena, he inferred that then 
were invisible rays of pure caloric in the light of the sun, which 
were less refrangible than even red light. 

The following are the measures of the temperature of the different 
rays. 

Color. Temperature. 

Blue, 56° Fahrenheit. 

Green, - 58° 

Yellow, 62° " 

Red, 72° « 

Beyond red, 79°. " 

137. Chemical rays. There are in the spectrum, invisible 
rays beyond the violet, which give to light its power of produc- 
ing certain chemical phenomena. 

Exp. Moisten some white paper with solution of the nitrate of silver, 
(lunar caustic,) and lay it in the sun, the paper will be blackened ; the nitrate 
being decomposed by the agency of light. The durable ink used for marking 
linen, is made of the same material, and is blackened by the same means. 
If the moistened paper is exposed to the action of the spectrum, the greatest 

135. Illuminating power of the different rays. Experiments to show the 
effect of absorption on color. 

136. Calorific rays. Heating power of the colored ra} r s. Dr. Hcrschel's 
experiments. Temperature of the different rays. 

137. Chemical rays. Experiments. 



SOURCES OF LIGHT. 51 

effect "will be perceived just outside of the violet ray : and the action de- 
creases, in receding from that till it becomes scarcely perceptible. The 
chemical agency of light is, therefore, attributed to certain invisible rays, 
more refrangible than the violet, and which are called the chemical or 
deoxydizing rays ; and if any of the colored rays seem to possess the same 
power, in a degree, it is probably owing to the imperfect refraction, which 
does not completely separate them. 

138. The most refrangible rays possess also the property of 
rendering steel or iron magnetic. This property is most re- 
markable in the violet. Photographic drawing depends on the 
agency of these rays. 

Exp. Let one side of a plate of glass be covered with bees-wax, colored 
with lamp-black, and a picture be drawn On it by a sharp point which 
removes the bees-wax. On a piece of white paper spread a solution of 
salt in water, and pour upon it a solution of the nitrate of silver, there will 
be a formation of chloride of silver. Let this paper be placed over the 
glass, and thus exposed to the Sun's rays ; these passing through where the 
wax is removed, a picture is formed upon the paper, by changing the 
chloride black wherever the light strikes it. 

Exp. In a saturated solution of bichromate of potassa let a piece of 
paper be soaked, then dry it quickly, and place it in the dark. Let draw- 
ings, dried plants, or writing be laid over this, and exposed to the Sun, a 
yellow copy of them will appear while the ground will be orange. To fix 
the image, the salt which has not been acted upon by the light should be 
dissolved by carefully washing, when the image will appear white, the 
orange ground still remaining. 

Daguerreotype. This name has been applied to a method 
recently discovered by Daguerre, of fixing the impression of 
images on plates of silvered copper, cleansed with nitric acid 
and exposed to the vapor of Iodine. 

The process is effected by placing a prepared plate in a 
Camera Obscura in such a manner that the light will come 
directly from the object to be impressed to the plate— where, 
if the light be sufficiently strong, a perfect image will be formed 
in 10 or 15 minutes. This plate must be heated to 167° Fahr., 
and exposed to a vapor of mercury, at an angle of 48°, it must 
then be submitted to the action of hyposulphate of soda — and 
cleansed in distilled water. 

The chemical rays, are the most refrangible, the calorific, the 
least so, while the colorific possess a mean degree of refrangi- 
bility. 

139. The principal sources of light, are ; 1st, the sun and 
fixed stars ; 2nd, incandescent or heated bodies ; 3d, phosphorescent 
bodies. 

140. A solid body heated to between 600° and 700°, begins 

138. Magnetic rays. Refrangibility of the three kinds of ravs. 

139. Sources of light. 

140. Incandescent bodies. Flame. Cause of the luminous appearance 
of flame. Faint light of the flame of hydrogen. 



52 LIGHT. 

to be luminous in the dark, and glows by day light, at about 
1000° j it is then said to be incandescent. The color of incan- 
descent bodies, changes as the heat is raised, passing through 
the shades of cherry red, dull red, bright red, up to a white 
heat. Flames consist of incandescent, gaseous matter, and their 
temperature is far above the white heat of solids. The luminous 
property of flame is derived from solid matter diffused through 
it ; and its illuminating power is not at all in proportion to its 
heat : for the heat of flame is, under certain circumstances, 
known to be very intense, when the light which it emits is ex- 
ceedingly feeble. Hydrogen gas is considered the purest form 
of flame which can be exhibited, and yet the light which it emits 
is so faint that, in day-light it can hardly be seen ; while its 
heat is so intense, that an iron wire held in it, will soon be 
melted or burned. In this process, the hydrogen will become 
exceedingly luminous, as the metallic wire ignites. By scatter- 
ing fine dust, such as sifted magnesia, or any other solid sub- 
stance, not of itself inflammable, upon the pale flame of hydrogen, 
its light will be greatly increased. 

141. The brilliancy derived from the flame of our common candles and 
lamps, is chiefly owin« to the carbon blended with the oily substances, and 
burning in the flame. If this substance exists in too large a quantity, it 
will cause the flame to throw off a disagreeable smoke, offensive to the 
smell, and injurious to the walls and furniture of a room. 

142. As flame depends upon an' intense heat for its existence, consequently 
anything that will reduce its temperature, that is, anything that will cool 
it, will extinguish it. A small flame for instance, will be extinguished by 
bringing a large mass of cold iron near it ; the metal absorbs the heat. 

143. Phosphorescence. Some animal bodies during life, and 
some animal and vegetable bodies, such as fish and certain kinds 
of wood, in a state of putrefaction, give out silvery light, which 
is termed phosphorescent. The sea, also when agitated at night, 
appears phosphorescent. Thus the track of a vessel is often 
marked by a line of soft and beautiful light, formerly supposed 
to be owing to phosphorescent matter held in solution. But ac- 
cording to some late observations, this luminous property of the 
sea, is owing to collections of minute ovae or eggs of animalculae, 
which float in slimy masses over the water. Some bodies give 
out phosphorescent light only when heated ; thus lard, tallow, 
&c. exhibit this property at, or near the boiling point. A mineral 
called Chlorophone, lime, and some other mineral substances, 
phosphoresce when heated. Solar phosphori are bodies which 
after having been exposed to the sun's rays, are luminous in 

141. Flame of candles and lamps. 

142. Flame extinguished by withdrawing caloric. 

143. Phosphorescent light. Its cause. Photometers. 



SOURCES OF LIGHT. 53 

the dark, at common temperatures. Some suppose the phos- 
phorescent property of these bodies, is owing to their absorbing 
the sun's light, and giving it off unchanged in the dark, the 
lighter body imparting light to the darker one, as a warmer 
body imparts caloric to a colder one. But as these are artificial 
substances prepared with sulphur, charcoal and other highly 
inflammable materials, the light which they give offin the dark, 
may be owing to slow spontaneous combustion, or the combina- 
tion of the sulphur, &c. with the oxygen of the air. 

The Bolognian phosphorus is prepared by matin? into small rolls, sulphate 
of baryta, and heating them in beds of fine charcoal. Baldwin's phosphorus 
is nitrate of lime fused at a low heat. Canton's phosphorus is made by heat- 
ing oyster shells to redness, with sulphur. 

Photometers* are instruments for measuring the intensity of light ; Leslie's 
photometer consists cf a differential thermometer, of which one bulb is black, 
and the whole inclosed within a glass shade. It depends on the principle 
that solar light is always accompanied with an equal proportion of heat. 
The white bulb transmits all the light and heat, and therefore is unaffected 
by either ; the black bulb absorbs all the rays, andheats the air within ; the 
consequent expansion of air in the black bulb, will impel the liquid to rise 
in the white one, in a degree corresponding to the intensity of the light. 

144. Theories respecting the nature of light. We have con- 
sidered light under the head of imponderable agents, on account 
of its connexion with caloric and electricity. The Newtonian 
theory considers light as a material, imponderable fluid, proceed- 
ing from luminous bodies in all direction, and producing by its 
effect on the organs of sight, the sensation of vision ; — Another 
theory, called the undulatory theory supposes rays of light to be 
produced by the rapid motion or vibration of an elastic medium 
which pervades all space ; and that these vibrations produce 
by their action on the retina of the eye, the sensation of vision, 
as the vibrations of air produce upon the auditory nerve the 
sensation of hearing. 

* From phos, light, and metron to measure. 

144. Theories respecting the nature of light. 
5* 



54 LIGHT. 



CHAPTER VI. 

GALVANISM, OR VOLTAIC ELECTRICITY. 

145. The subject of Electricity* is intimately connected both 
with Natural Philosophy and Chemistry. As a chemical agent, 
it is chiefly confined to the department of Galvanism. 

History of Galvanism. The earliest notice of any fact con- 
nected with Galvanism is found in a book entitled " The general 
theory of Pleasures," published in 1767, by a German metaphy- 
sician named Sultzer. It is there mentioned that a peculiar 
taste is excited when two slips of different metals, one lying on 
the tongue, and the other under it, are made to touch each other. 
This writer, however, gave no satisfactory explanation of the 
phenomena ; and it attracted little attention till 1790, when it 
acquired importance from the discovery made by Galvani a 
distinguished professor of Anatomy at Bologna ; this philosopher 
had for some time, entertained the opinion that electricity was 
concerned in producing the muscular motions of animals ; and 
his belief was strengthened, by observing, that when the limbs 
of some recently skinned frogs, lying on his table, were acci- 
dentally touched with a knife (the electric machine being in 
operation at the same time) convulsive motions were produced. 
In pursuing his researches on the subject, he found that the same 
result would be obtained, whenever two metals were made to 
touch each other, while one was in contact with the nerves, and 
the other metal in contact with the muscles of the frog. 

Fig. 29. 




The figure represents, at a a, nerves in the leg of a frog, from which the 
skin is removed ; at b is a silver wire passed under the nerves. A piece of 
zinc c c, being now brought into contact both with the silver, and a muscular 
or fleshy part of the legs, the Galvanic effects are exhibited. 

* For a condensed view of Electricity see the author's large work on 
Natural Philosophy. 

145. Electricity as a chemical agent. History of Galvanism. Obser- 
vations and experiments of Galvani. 



GALVANISM. 55 

Galvani concluded that the nerves and muscles of living ani- 
mals, are charged with electricity developed in the brain ; and 
that, whenever a communication is made between them by- 
means of a conductor, the equilibrium is restored, and motion 
produced. 

146. Among the many who zealously examined and discussed 
these new phenomena, was Volta, a distinguished electrician of 
Pavia. He made numerous experiments on the subject, and 
arrived at the conclusion, that the motions were, indeed, produced 
by electricity, not generated, however, as Galvani supposed, in 
the animal system, but excited by the contact of the metals, them- 
selves. But notwithstanding the identity, now well established, 
of common electricity with the Animal electricity of Galvani, 
certain modifications of its character and applications, as well 
as the different modes of producing it, have caused the name 
Galvanism to be still retained. Volta constructed the pile of 
metallic plates which is distinguished by his name, and has 
greatly contributed to the advancement of chemical science ; it 
is now superceded by improvements upon the original invention. 

Before we describe the effects of the Voltaic pile, it is necessary to premise 
the following facts. 

1st. Whenever two plates of different metals, are made to touch each other 
by their broad surfaces., electric excitement is produced. 

2nd. If the plates be separated by means of an insulating handle, one of 
them will be found positively and the other negatively excited. 

3d. The plates being of equal surfaces, the positive excitement of one, 
will be equal in intensity to the negative excitement of the other. 

4th. Other circumstances being the same, the degree of excitement will 
be the greater, as the metals differ more in their degrees of affinity for 
oxygen. 

5th. The more oxydable of the two metals will always become positively 
excited, and the other negatively. 

14-7. Zinc and copper, are the metals commonly used in gal- 
vanic experiments. 

The cut represents a vessel (Fig 30,) con- Fig. 30. 

taining an acid, much diluted with water, and 
two plates, the one of zink, the other of copper, 
(as shown by the letters Z and G ;) to each 
plate is soldered a piece of wire, the two ends 
of which meet in the center, opposite the place 
of insertion. This is called a simple galvanic 
circle. It is supposed that when in operation, 
there is, in such a circle, a continued current 
of electricity, flowing in the direction of the arrows from the zink to the 
fluid, from the fluid to the copper, and from the copper back to the zink. 

146. Conclusions of Volta. Voltaic pile. Facts connected with the 
developement of electricity by means of the Voltaic pile, or Galvanism. 

147. Metals commonly used in galvanic experiments. Galvanic circle. 
Negative and positive poies. 





56 LIGHT. 

When the wires do not communicate, the galvanic circle is said to be broken. 
The wire attached to the copper plate is negative, that to the zink plate 
positive. The wires are also called poles ; thus we say, the copper is the ne- 
gative pole, and the zink, the positive pole. 

148. The quantity of electricity developed by a single pair of plates being 
very small, Volta endeavored to devise means of increasing it ; and was 
finally led to the invention of the Voltaic Pile. This instrument consists of 
pairs of zink and copper plates, one above another. Each pair is called a 
simple element of the pile, the whole consisting of a series of simple elements 
or circles. Between each pair of plates is placed a piece of cloth wet with 
weak acid. 

The figure represents a Voltaic pile, (Fig. 31,) 
commencing with zink, Z, and ending with cop- 
per C. The wires which meet in the center are 
the two poles. The direction in which the ar- 
rows point, is that of the electric current. In 
constructing the Voltaic pile, from thirty to fifty 
plates of copper, and as many of zink, are gen- 
erally used ; these are placed in regular order, 
each pair of plates being separated by a piece of cloth ; thus a regular suc- 
cession of copper, zink and cloth, is kept up through the whole series. The 
pieces of cloth should be somewhat smaller than the metallic plates, and 
should not be so moist as to yield any of the liquid by the pressure of the 
superincumbent metals. The pile is contained in a frame composed of a 
base and cap of dry varnished wood, connected by stout rods of glass. 

149. The pile is capable of affecting the electrometer, and of producing 
muscular action in a much greater degree than the single pair of plates. 
The zink being positive and copper negative, the electric equilibrium is 
restored on bringing them into communication by means of wires con- 
nected with each ; as it is when the coatings of a charged Leyden phial 
are connected. But the causes of excitement being still in the pile, the 
equilibrium is instantly disturbed again, so that a continuous stream of the 
galvanic fluid is produced : that is one of the most striking differences be- 
tween the action of the pile and that of the common electric machine. By 
means of the pile, the Leyden phial may be charged and the effects of the 
latter are precisely the same as when charged in the usual manner. If the 
two extremes of the pile are touched at once by the moistened fingers, a 
shock is felt differing little in kind from that produced by the phial, but 
much less in degree ; but if, after the first effect, the contact be still kept 
up, a continuous and painful thrilling sensation is perceived ; and if the 
electric current traverses any wound, burn, or excoriation, it causes.it to 
smart severely. Volta remarked that the pain was greater on the side 
toward the negative pole ; a circumstance in which Galvanism resembles 
common electricity. 

150. Any number of piles may be combined by connecting the extreme 
copper plate, or negative pole of the first, with the extreme zink plate, or 
positive pole of the second, and so on ; and all the effects of the pile will be 
increased according to the number of simple elements, or pairs of plates. 

148. Construction of the Voltaic pile. Number and arrangement of 
plates. 

149. Action of the Voltaic pile. Differences and resemblances in the 
action of the Voltaic pile and the electrical machine. 

150. Connection of piles. 



GALVANIC BATTERY. 



57 



This form of the pile is not now in use, as others more powerful and more 
convenient have heen substituted. 

151. One of the first of these was Cruickshank's trough, (Fig. 32.) com- 
monly called the Galvanic batter)' ; it consists of a trough of dry wood, divi- 

Fig. 32. 



y » " _ " '" " 




ded into cells, by partitions placed at equal distances ; each partition is made 
of a plate of zink, and a plate of copper previously soldered together and 
fitted accurately into a groove cut in the wood ; the joints being made 
perfectly tight with cement. The same order of arrangement must be 
observed as in the pile. This instrument is put into operation by filling all 
the cells about two thirds full of a saline or acid solution. Its effects are 
more powerful than those of the pile, and may be increased by connecting 
several troughs in the manner we have just described, (see § 150). 

152. The actual contact of the metals, is not necessary, as is seen in 
the construction of Yolta's chain of cups, (Fig. 33.) commonly known as the 
« Couronne des Tosses."* This Fig. 33. 

arrangement, of which the ef- 
fects are greater than those of a 
pile of equal dimensions, consists 
of any number of pairs of zink 
and copper plates generally about 
one and a half inch square ; the 
zink and copper plate of each 
pair are connected by a wire 
bent in the form of an inverted 
U : and the different elements 
are immersed in cups or glasses 
of acid, or saline liquids, in such 
a manner that the zink plate of 
one pair shall be in the same vessel with the copper of the succeeding. 
Thus the different cups are connected only by the wire which joins the two 
members of each element : and the different elements act on each other only 

* Couronne des Tasses, pronounced koaron da tas } literally a crown of cups. 




151. Galvanic battery. 

152. Couronne des Tasses. 



58 



GALVANISM. 



through the medium of the intervening liquid. The two extreme plates 
which are not immersed in the liquid, are not taken into the account, and 
may be used as means of connecting the two poles of the row. 

The electricity is supposed to be excited by the mutual action of the sur- 
faces of zink and copper, opposed to each other in the same cup, and is 
conveyed from one cup to another by means of the wire which connects two 
successive cups. 

153. Modifications of the Galvanic Battery. Dr. Wollaston observing 
that in the trough of Cruickshank, the effect of one zink and one copper 
surface in each pair was lost, by soldering them together, he proposed to 
use double copper plates or to bend the copper plate so that it should en- 
tirely surround the zink one, but without allowing the two to touch each 
Fig. 34. other, (see Fig. 34.) In 

this way each zink sur- 
face z, is opposed to one 
of copper, c, and the pow- 
er is increased by one 
half. Batteries are now 
generally constructed on 
this principle : and a fur- 
ther improvement is made 
by connecting all the 
plates to a bar of dry 
wood, by means of which 
they can be removed at 
pleasure ; the trough is 
made of porcelain or some 
other nonconductor, and 
is divided into cells by 
partitions of the same 
material. 

The largest battery 
ever constructed is that 
of Mr. Children the plates of which were 6 ft. long, and 2 ft. wide. 




Fig. 35. A. 




Hare's Calorimoler, (or mover 
of heat, (Fi?.35.A.) consists of a 
number of square zinc and 
copper plates of any convenient 
size, alternating with each 
other in a wooden frame. Two 
rectangular tubs accompany tlie 
apparatus, one containing the 
liquid acid for exciting the 
electricity, and the other to hold 
water for washing the plates. 
By means of an upright cross 
bar with a rope and pulley, the 
frame containing the plates 
may be at pleasure immersed 
in, or removed from the acid 
liquid: and this facility affords 
great advantages : lor it is as- 
certained that the greatest ac- 
tion of the galvanic battery is 



153. Dr. Woliaston's improved battery, 
rimoter. Deflagrator. 



Mr. Children's battery. Calo- 



GROVES CONSTANT BATTERY. 



59 




at the first instant of immersion; and it is, therefore, important to be able 
to immerse all the plates at once. Besides the effects of the calorimoter in 
igniting wires, during its action much hydrogen is evolved from the liquid, 
and the gas is sometimes inflamed by the great heat produced. (The figure 
at 1, represents the entire instrument ready to be plunged, and at 2, the top 
of the plates.) 

Another modification of the battery by Dr. Hare is called the Deflagrator 
from its great power of burning the metals. 

The battery most Fig. 35. B. 

used at present, 
and which seems 
likely to super- 
cede the use of 
all others, is called 
Groves' Constant 
Battery, a section 
of which is repre- 
sented at (Fig. 35, 
b.) a, a, a, the 
outer glass vessels 
or tumblers ; b, b, 
b, cylinders of 
zink, open above 

and below ; c, c, c, porcelain cylinders closed at the bottom, to receive the 
platina slips ; d, d, d, bars of zinc connecting the zinc cylinder in one tum- 
bler with the platina slip of the next ; e, e, e, platina slips attached to the 
end of the zinc bars. 

When in use, the outer glass vessel is filled with dilute sulphuric acid, 
and the inner porcelain vessel with strong nitric acid, and a connection be- 
ine established between the platina slip at one extremity and the zinc 
cylinder at the other as represented by the dotted lines, the galvanic current 
then flows in the direction indicated by the arrows. 

154. Effects of Galvanism. While the phenomena of galvan- 
ism and electricity seem to be produced by the same agent, they 
differ remarkably in the following particulars, viz : 1st, in the 
greater quantity of the electric fluid developed by the galvanic 
battery, 2nd, in its low intensity, and 3d, in the incessant renewal 
of the excitement as often as the equilibrium is restored, so a? 
to produce a continuous current. To the last circumstance, i 
attributable the superiority of galvanism over electricity, in 
producing chemical decomposition. 

155. The igniting effects of the galvanic pile are very re- 
markable. 

When the two poles of a battery in action are connected by a 
small wire, the latter becomes intensely heated and gives out a 
light so vivid, that the eye can scarcely endure it. With a 
powerful battery, substances not fusible by any other means, are 
melted almost instantly. Even platinum is melted by it, as 



154. Difference between electricity and galvanism. 

155. Igniting effects of galvanism. Exp. 



60 GALVANISM. 

readily as wax by the flame of a candle. Of all substances, 
charcoal emits the most intensely, brilliant light. 

Exp. Two slender slips of dense charcoal, or of plumbago,* should be 
selected, scraped to a point, and fixed to each of the connecting wires. The 
battery being now put into action, and the charcoal points made to touch by 
means of insulating handles attached to the connecting wires, they imme- 
diately become vividly ignited ; and if very slowly separated, an arc of in- 
tense light will fill the space between them. With the great battery of the 
Royal Institution at London, consisting of 2000 pairs of plates an arc ap- 
peared four inches in length, and the heat existing there was so great as t» 
fuse whatever substance was placed in it. Wires, even of the least oxidabi- 
of the metals, being made the medium of connection between the poles, may 
be burnt almost instantly. 

156. Brilliant combustions may be exhibited in the following manner. 
Place some mercury in a flat dish and connect it with the negative pole of a 
strong battery ; attach to the positive wire whatever is to be subjected to 
experiment, and make it touch the surface of the mercury. A point of fine 
iron wire burns in this manner with great rapidity, giving oiF vivid sparks 
in all directions, and producing an appearance like that of a brilliant star; 
the reflection from the bright surface of the mercury adding to its beauty. 
Gold-leaf burns with a beautiful green light the instant it touches the mer- 
cury, and is immediately converted into the purple oxide of gold. Silver and 
copper leaf, and even platinum wire, undergo vivid combustion. It is ne- 
cessary to keep the surface of the mercury quite clean during these experi- 
ments, that its conducting power may not be impaired. 

157. If the two connecting wires of a battery are immersed 
in water, so that their points shall be within a short distance of 
each other, an effervescence, arising from the evolution of gas, 
will be immediately observed ; and the experiment may be so 
conducted, that the gas can be collected. When collected, it 
will be found to consist of oxygen and hydrogen, mixed in pre- 
cisely the proportion for forming water. The kydroge?i is always 
evolved at the negative pole, and the oxygen at the positive, and by 
a contrivance of Dr. Wollaston, they may be collected and ex- 
hibited separately. 

This little instrument consists of a bent 
glass tube. At the bend is a small hole 
through the lower side of the tube ; each 
leg of the instrument is corked air tight. 
Through the corks, two platinum wires are 
passed, extending through the whole lengths 
of their respective portions of the tube, and 
almost meeting each other at the angle. If 
this instrument be immersed in a vessel of 
water, and each of the wires connected 
with one of the poles of a galvanic battery, 
rrr^r^. the two portions of the tube will shortly be 
found to contain gas; that in the positive 
part will be oxygen, in the negative hydrogen ; 
and the hydrogen will be in bulk, twice that 
^f^^JTTT of the oxygen; such being the proportions 

156. Combustion of substances placed on mercury by means of the bat- 
tery. 





DECOMPOSITION OF WATER. 61 

in which the gases unite to form water. But it is not necessary that the 
water decomposed, should he all in the same vessel. The experiment suc- 
ceeds equally well, if two straight tubes, Fig. 37. 
open at their lower end, are immersed in 
separate vessels of water, provided the two 
vessels communicate by means of moisten- 
ed fibres of cotton. To effect the decom- 
position of water, only a weak galvanic 
battery is required ; the voltaic pile, or a 
trough of 12 pairs of 4 inch plates being 
sufficient. Other compounds, of which the 
constituents are united by a stronger force, 
may be resolved into their parts by propor- 
tionally increasing the number of plates. 

158. In proceeding to consider, 
the decomposing effects of galvan- 
ism, it is necessary to explain some 
of the Chemical properties of acids 
and alkalies.* 

Chemical properties of acids and alkalies. Acids have the 
property of changing to red, the blue color of certain vegetable in- 
fusions, as that of violets, or of purple cabbage. Alkalies, on 
the contrary, change the same blue infusions green ; and a color 
which has been changed by one of these substances, may be 
restored by a sufficient quantity of the other. Salts are chemical 
compounds of an acid and an alkali ; and when the two are 
united in proper proportions, their characteristic properties are 
entirely disguised, and the salt is called neutral. 

159. If we dissolve in water, Glauber's salt or sulphate of soda, 
(composed of sulphuric acid and soda,) and add to the solution, 
a little of the blue infusion of cabbage, the color will remain 
unaltered shewing that the compound is neutral. Let this solu- 
tion be subjected to the action of a galvanic battery of sufficient 
power, the liquid at the positive tube, will soon become red, 
proving the presence of an acid there, while at the same time, 
the negative tube will exhibit an alkali, as will be shown by the 
liquid in it, becoming green. Now this acid and alkali could 
only arise from the decomposition of the sulphate of soda ; and 
we are able, otherwise, to show that the contents of the two 
tubes, being mixed, will reproduce this salt. The sulphuric 
acid, and soda are both compounds, each containing oxygen, 

* This subject is more fully explained at § 180. 

157. Decomposition of water by means of the battery. Experiment with 
a bent glass tube. Experiment with two strait tubes. 

158. Characteristics of acids, alkaUis, salts. 

159. Decomposition of a salt by the galvanic battery. What would be the 
ultimate analysis of Glauber's salt ? 

6 



62 GALVANISM. 

united to a peculiar combustible body ;* and by a galvanic ar- 
rangement of high power, the acid and alkali are resolved into 
their elementary parts, that is, to their ultimate analysis. 

160. In all cases of proximatef analysis of salts, by the gal- 
vanic battery, the acid will be found at the positive pole, and the 
alkali at the negative ; and, whenever by ultimate analysis in 
this manner we resolve a substance into elements, of which one 
is combustible, and the other non-combustible, the latter will be 
found at the positive, and the former at the negative pole. 

Mr. Faraday, who has paid much attention to the subject of galvanism, 
advances the following opinions : — 

1st. That the poles have no attractive, or repulsive tendency. He prefers 
the term electrodos,% which signifies the way or door for electric currents. 

2d. When a compound is decomposed by galvanism it is said to be elec- 
trolyzed ; || the substances capable of decomposition are called electrolytes ; 
the elements of an electrolyte are called ions.§ Electro-negative substances 
as oxygen, chlorine, acids, &c, he calls anions ;1T the electro-positive as 
hydrogen, alkalies, metals, &c, he calls calwis** 

3d. Most of the simple elements are ions, that is capable of forming 
compounds decomposable by galvanism. 

4th. A single ion by itself has no tendency to pass to either of the elec- 
trodes, or is indifferent to the voltaic currents. 

5th. To account for the decomposition of water by galvanism, Mr. 
Faraday supposes a line of particles between the two electrodes, along which 
the current passes. When a particle of oxygen is evolved at the positive 
electrode, its hydrogen is not at once transferred to the opposite electrode, 
but unites with the oxygen of the contiguous panicle of water, on the side 
towards which the positive current is moving, then it passes to the next, 
and so on till it arrives at the pole. A similar row of particles of oxygen 
start from the negative electrode at the same moment and combine success- 
ively with the particles of hydrogen as they pass them on their way to the 
positive pole or electrode This process is supposed similar to what takes 
place in all cases of galvanic decomposition. 

161. Discoxieries of Sir H. Davy. The Galvanic battery be- 
came in the skillful hands of Davy, the means of effecting the 
most brilliant discoveries. With this instrument, he ascertained 
the compound nature of the alkalies and earths, a fact which, 

* Sulphuric acid is composed of sulphur and oxygen, soda of a metal called 
sodium united with oxygen. 

f The analysis of sulphate of soda into the acid and the alkali is the 
proximate, analysis; the farther analysis of sulphuric acid and soda into 
three simple elements is the ultimate or last analysis. 

X From the Greek electron, and odos, a way. 

|] From electron, and lus, to unloose or disengage. 

§ Pronounced i-ons, from ion, going, participle of the verb to go. 

IT From ana, upwards, and odos, the way in which the sun rises. 

** From kala, downwards, the way in which the sun sets. 

160. What takes place in all cases of proximate and ultimate analysis of 
salts by the galvanic battery ? Mr. Faraday's theory of decomposition. 

161. Decompositions effected by Davy. Strong proof of the elementary 
nature of a body. 



DISCOVERIES OF SIR H. DAVY. 63 

previously had been only suspected. This discovery has intro- 
duced a new era in the annals of Chemistry, and added several 
new metals to the list of simple elements. No known compound 
has been able to resist the decomposing power of galvanism j 
and it is regarded as the strongest proof of the elementary or 
simple nature of a body, when it gives no signs of decomposition, 
on being subjected to the influence of this agent. 

162. To account for the decomposing effect of galvanism, it 
is necessary to recur to the principle of electric attraction and 
repulsion. If two particles, united to form a compound mole- 
cule, are both brought into the same electrical state, they will 
exert a mutual repulsion ; and if this repulsion be more powerful 
than the force of their chemical attraction, they must necessari- 
ly separate, and the compound will be destroyed. Or, even if 
they be in opposite states of electricity, since they are both within 
the influence of the battery, that particle which has the strongest 
tendency to become negatively electric, will naturally become 
so by induction, and be attracted to the positive pole ; and at 
the same time, a similar change in the opposite direction, will 
take place with the other particle. 

163. Davy was led to infer that chemical and electrical at- 
tractions are effects of the same cause. Having brought a dry 
acid in contact with a metal, he found that the former became 
electro-negative ; an alkali, treated in the same manner, became 
electro-positive ; and when an acid and an alkali, both dry, were 
made to touch each other, electrical excitement was produced, 
the acid being negative and the alkali positive. 

Furthermore, those bodies which exhibit the greatest tendency to chem- 
ical combination, are also prone to assume opposite electrical states ; and 
though two bodies, A and B, which, if successively brought in contact with 
C, would each assume the same electrical state, may be in opposite electri- 
cal states when in contact with each other ; yet if they combine, their 
compound A B, is held together by weak affinities, and is easily decomposed. 
Examples of this kind may be found in the instances of chlorine and oxy 
gen ; each of these bodies is strongly electro-negative, when in contact with 
hydrogen, and each forms with it, a well-defined compound. But chlorine, 
though electro-negative when compared with almost all bodies, is electro- 
positive with regard to oxygen, and may be made to combine with it ; yet 
the compounds formed by chlorine and oxygen, are decomposed with re- 
markable facility. 

164?. The electro-chemical theory, supposes the same electri- 

162. Explanation of the decomposing effect of galvanism. Why com- 
pounds are destroyed by electrical repulsion. Why there should be a de- 
composition when the particles are in opposite states of electricity. 

163. Davy's experiments to prove the connection between chemical and 
electrical attractions. Electricity of acids and alkalies. A body may be 
electro-positive with one body, and electro-negative with another. Why 
chlorine and oxygen form compounds which are easily decomposed. 



64t GALVANISM. 

cal excitement to take place between atoms in contact with each 
other, as we have seen to be produced by masses ; that the atoms 
remain in contact, that is to say, in combination, in consequence 
of the electrical attraction consequent on this excitement ; and 
that their union ceases, whenever, by any cause, they are brought 
into the same electrical state, or when they are exposed to the 
action of any third body which is more highly excited than 
either ; for, in the latter case, the highly excited body will at- 
tract the particle which is dissimilarly excited, and repel that 
which is similarly so ; and this is what happens in the decom- 
position of a compound substance by the galvanic battery. 

165. Following the same course of reasoning which led him 
to the discovery of the alkaline metals*, Davy made other useful 
applications of his theory. Although the metals, compared with 
oxygen, are all electro-positive, yet when compared with each 
other, as in the case of zinc and copper, they may have opposite 
natural electric energies ; and from experiment, as well as from 
theory, it is shown, that the positive metal will have the strongest 
tendency to combine with oxygen. Thus copper is rapidly corrod- 
ed in acid, or saline solutions ; but in contact with zinc, iron and 
some other metals, copper becomes electro-negative, and remains 
bright, while the other metal is rapidly oxidized j this happens, 
also, in the galvanic battery. 

Davy found that a slip of zinc or iron, would protect from rust 150 times 
its surface of copper, though constantly exposed to the action of salt water; 
and he proposed to apply this principle to the preservation of the copper 
sheathing of ships. The rusting of fine iron or steel instruments, may be 
effectually prevented by fixing a piece of zinc in their handles or elsewhere, 
so that it shall be always in contact with the blade. 

Electro-Magnetism or Magnetic effects of Electricity. 

166. The relations existing between magnetism and electrici- 
ty are daily becoming more fully developed, and present a most 
curious subject of philosophical research ; the facts already ac- 
cumulated constitute a new branch of physical science called 
Electro-Magnetism . 

167. Professor Oersted of Copenhagen, in 1819 discovered that 
the metallic wire of a voltaic circle causes a magnetic needle 

* Sodium, potassium, &c. being metals found in the alkalies, soda, potash, 
&c. are termed alkaline metals. 

164. Electro-chemical theory founded upon the preceding facts. 

165. Applications made by Davy of his theory, with respect to the elec- 
trical attraction of the metals. Why copper is protected from rust or 
oxidation, by zinc or iron. Iron and steel protected by zinc. 

166. Electro-magnetism. 

167. Discovery of Oersted. 



GALVANOMETER. 65 

when brought near it to deviate from its natural position. This 
discovery was a confirmation of what was generally supposed, 
viz ; that electricity might be employed to communicate mag- 
netic properties to iron or steel. It had been observed, that a 
ship having been struck with lightning, the magnetic needle 
often had its polarity destroyed or reversed, and that the iron 
about the ship became magnetic. 

168. Galvanometer. It being proved that every part of a wire 
in a closed voltaic circuit exerts an equal force upon the poles of 
a needle, the combining force will be increased by increasing 
the number of points. This can be done by coiling the wire 
into the form of a circle or rectangle ; the united force will de- 
pend on the number of coils, each coil exerting its own peculiar 
force. 

e d *%. 38. a 

y? ^ d, e, (Fig. 38,) are the two ends 

of a copper wire bent in the form 
of a rectangle, in the centre of 
which, and in a plane perpendi- 
cular to the plane of the wire, is 
placed a magnetic needle. A 
graduated circular plane mea- 
sures the degree cf declination 
of the needle, which indicates 
the quantity of electricity circu- 
lating along the wires. If the positive voltaic current pass above the 
needle from north to south, or which is the same thing from e to a, and 
then pass around the south pole from a to 6, the effect will be doubled. 
The deflection of the needle may be increased by multiplying the coils, until 
its directive power shall be wholly destroyed, or even reversed. If at the 
moment the needle has attained this point, the voltaic currents be sent in 
an opposite direction, it will perform a revolution. Thus a needle may be 
made to revolve rapidly by changing the direction of the currents. 

Influence of voltaic currents on soft iron or steel. 

169. If instead of the common magnetic needle, an iron or steei 
needle be suspended in the galvanometer, at right angles to the 
conducting wires, permanent magnetism will be communicated 
to the steel, and the iron will become powerfully magnetic, but 
will lose this property when the voltaic currents cease to cir- 
culate. This discovery was made about the same time by M. 
Arago and Davy. 



168. Galvanometer. Explanation of the figure. 

169. Discovery of Arago and Davy. Explanation of Fig. 39. Expla- 
nation of Fig. 40. 

6* 




66 



GALVANISM. 



Fig. d 39 




Let an insulated copper wire be coiled in the 
form of a helix, as at d, connect the two ends of 
the wire fc, b, with the cups c, 2, into which the poles 
of a battery may be inserted. If bars of soft iron or 
steel be placed in the coil, they will become 
magnetized the instant the voltaic currents begin 
to circulate around the coil. If the positive 
current flows from z around the coil, n will be 
the north pole and s the south pole. The poles 
will be reversed if the positive current flews 
from c. 

The magnetic properties of soft iron, 
though not retained, are very powerful 
while the voltaic currents are passing around it. 

Fig. 40. If a soft iron cylinder, about two inches in diame- 

ter and bent in the form of a horse-shoe magnet 
h, (Fig. 40,) be wound with copper-wire, and the 
ends a, b, connected with the battery, it will become 
a powerful magnet. On applying the armature'i 
it will be found capable of sustaining immense 
weights ; — magnets of this kind have been made to 
support from one hundred to a ton weight. The 
principle is the same as in the helix, (Fig. 39,) and 
a as in the galvanometer, (Fig. 38,) where by increas- 
,/ing the number of coils, the magnet becomes more 
powerful ; but the force does not increase directly 
as the number of coils ; for each additional coil is 
farther from the axis of the iron bar, and the power 
it exerts is inversely as the square of the distance 
from the axis. 

170. Volta- Electric Induction. It having 
been found that an electrically excited body, 
induced electricity in other bodies brought 
near it, the fact was next discovered that the 
same effect is produced by electricity in 
motion. Let a copper wire be wound in the 
form of a helix, and the ends connected with 
a battery ; let another wire be wound around 
this, but insulated from it, and the ends connected with a gal- 
vanometer, currents of electricity will be induced in the insulated 
wire, as often as the battery current is broken. All the effects 
of galvanism may be produced by the insulated wire. 

* From artno, to arm a piece of soft iron applied to a loadstone, or con- 
necting the points of a horse-shoe magnet. 




J70. Volta-Electric Induction. Explanation of Fig. 41, Fig. 42. 



SEPARABLE HELICES. 



67 



Separable Helices, (Fig. 41.) 
exhibit the phenomena of volta- 
electric induction in a striking 
manner ; b is a hollow coil of 
coarse wire fixed upon a stand 
z ; one end of the wire is con- 
nected with the cup, and the 
other with the steel break-piece 
or non-conductor, which is fixed 
to the stand, by the side of the 
coil ; a is a coil of fine wire 
which may be placed over the 
coil b ; d is a bundle of wires 
which may be put into the 
copper coil c, and placed in the 
centre of the coil b. The entire 
apparatus is represented at 
Fig. 42. 

Exp. Connect one pole of 
the battery with the cup on the 
left of c, (Fig. 42,) and move 
the other pole along the break- 
piece ; vivid sparks will be pro- 
duced at each interruption. 

Exp. Place the coil a upon 
b, and let the currents circulate 
as before. If the handles e, /, 
(Fig. 42,) which communicate 
with the extremities of the wire 
forming the coil a, be held in 
the hands, powerful shocks will 
be felt, as the wire conveying 
the battery current passes 
across the break-piece. 

Exp. Remove from the wires 
rf, the copper coil c, and insert 
them gradually in the coil b 
while the currents are circulat- 
ing, and the sparks in the breaks 
piece will increase in brilliancy 
until the wires reach the bot- 
tom, when the greatest effect 
will be produced. 



Fig. 41. 




Ampere's Theory of Electro-Magnetism and Magno-Electricity. 

171. When two positive or two negative currents are passing 
in the same direction, and parallel, they attract, and when pass- 
ing in opposite directions, they repel each other ; — Supposing 



171. Ampere's theory and explanation. 



68 



GALVANISM. 



irqi 

if 'I 

la 



that all magnetic bodies, (the earth itself being included) derive 
their magnetic properties from currents of electricity circulat- 
ing, in reference to their axis, in one uniform direction of revo- 
lution, we are then able to account for all the phenomena of 
magnetism, electro-magnetism, and magneto-electricity. 
Fig. 43. Let us suppose that around the cylinder of steel 
(see fig. 43) at right angles to the axis, currents of 
positive electricity are constantly circulating in a 
direction opposite to that in which the sun moves 
The cylinder will be a magnet, n the north pole and 
s the south pole, and if it be poised upon a pivot, it 
will exhibit all the effects of the magnetic needle. 

Explanation. The needle turns to the east when the posi- 
tive current passes above it from north to south, because the 
currents in the magnet, and those in the wire, move in different 
directions. The needle is repelled, and turns so that the cur- 
rents may coincide. 

Bars of soft iron and steel become magnetic when placed in 
the helix around which currents of electricity circulate, because 
s similar currents are induced in them. 

The cause of the magnetic needle standing north and south, is on the 
theory of Ampere explained by supposing positive currents of electricity to 
be passing around the earth, in the direction in which the sun appears to 
move ; thus converting the earth itself into a magnet, its north pole corres- 
ponding to the south pole of the magnetic needle ; — if soft iron or bars of 
steel are placed in a north and south direction, they will become magnets 
by induction, the positive currents passing from west to east, because then 
they would coincide with the same currents in the earth which pass from 
east to west ; — therefore the magnetic needle stands north and south, be- 
cause the currents of electricity circulating around the earth, and those 
circulating in the needle, will coincide only when the needle takes that 
direction. 

172. Thermo-Electrical phenomena result from currents of 
electricity excited in metals by heat. If a magnet be suspended 
in a rectangle formed of a bar of antimony or bismuth, having 
its extremities connected with copper wires, and heat applied 
to one end of the bar, the needle will be deflected in one direc- 
tion, and when heat is applied at the other end, it will be de- 
flected in an opposite direction. This discovery was made by 
Leeheck in 1821. It has been found that a rotary motion may 
be produced by placing platinum and silver wires, soldered 
together in a circular form, upon a magnet, and applying heat. 

173. The Electro-magnetic Telegraph is an invention by which 
voltaic electricity is applied to communicate intelligence between 
distant places. At one station is the battery with wires extend- 
ing to the other station, and so connected with a magnetic needle, 



172. Thermo-electrical phenomena. 

173. Electro-magnetic telegraph. 



THEORIES OF GALVANISM. 69 

that when the wires are attached to the battery the needle is 
set in motion and by means of a pencil attached to it, those 
conventional characters are marked which are the symbols of 
certain words or ideas. The effects of this application of voltaic 
power in conveying intelligence with the rapidity of lightning, 
are beyond human calculations. 

174. Electrography is an application of voltaic electricity, by 
means of which may be produced perfect metallic casts or copies 
of medals, coins, copper-plates, &c. The instrument used is 
called the Electrotype. Its effect depends on the decomposi- 
tion of some metallic salt, by which the metal is precipitated 
upon the object to be copied, either forming a mould for the 
cast, or raising lines which may be used for making impressions 
on paper and other substances. 

B is a glass vessel (Fig. 44,) with divisions made 
by placing across it some porous substance as thick 
paste-board. Into one of the divisions is put a satu- 
rated solution of sulphate of copper, and the other a 
weak acid solution. The object C to be copied is 
soldered to one end of a wire, d, and a piece of zinc, 
Z, to the other end; the object is then immersed in 
the solution of copper, and the zinc in the acid solu- 
tion. Metallic copper then begins to be deposited 
upon the object C, copying, with perfect exactness 
the most minute lines and shades. In a few days a 
complete cast will be formed : this is separated from 
the matrix by gentle heat. 
Explanation. The sulphate of copper is decomposed into sulphuric acid 
and oxide of copper; — The acid, with the oxygen of the decomposed water 
go to the zinc ; while the hydrogen of the water and the oxide of copper go 
to the copper pole; the hydrogen unites with the oxygen of the oxide of 
copper, and the metallic copper is deposited upon the metal or object to be 
copied. 

Theories of Galvanism. 

175. 1st. The theory of Volta considers the contact of the metals to be the 
only cause of electric excitement ; it attributes to the liquid used, no other 
agency than that of conveying the electricity by means of its conducting 
power, from one pair of plates to the next, and thus enabling it to accumu- 
late at the poles. 

2d. The chemical theory is so called, because it regards the chemical action 
which goes on in the pile, viz., the oxidation of the zinc, as the original dis- 
turber of electric equilibrium. This theory, Dr. Wollaston supports by 
arguments drawn from various experiments. It is perfectly true, that the 
contact of the metals will produce electric excitement ; but it is also equally 
true, that electricity is developed during chemical action. Furthermore, it 




174. Electrography. Explanation of Fig. 44. 

175. Volta's theory of galvanism. The chemical theory. Electro-chemi- 
cal theory. Mr. Faraday's theory. Dr. Hare's opinion respecting the 

eating effects of the battery. 



70 CHEMICAL NOMENCLATURE. 

is observed that the activity of the pile is increased, when, by using a more 
powerful acid, the chemical action is rendered more violent. 

3d. Davy's theory, or the electro-chemical unites the two preceding ; it 
supposes that the electric equilibrium is first disturbed by the contact of the 
zinc and copper plates, and that the excitement is afterwards kept up, and 
increased by the chemical action between the liquid and the metal. 

4th. Mr. Faraday has attempted to prove that the poles have no attrac- 
tive or repulsive tendencies but merely afford a path for the voltaic currents 
to enter the liquid, or are doors for electric currents. 

5th. Dr. Hare does not attribute the heating effects of the battery to 
electricity, but supposes the fluid evolved by this machine to be a compound 
of electricity and caloric, in which the proportions of the two constituents 
vary according to circumstances ; thus, in the use of his calorimoter, great 
heat is excited, while the electric tension is very small. 

176. In examining the operations and effects of heat, light 
and electricity, it is not necessary that we attempt to theorize 
upon their nature, or to determine whether they are substances, 
or qualities of invisible substances. Such is the intimate con- 
nection between them that many philosophers suppose them to 
be modifications of the same power, or substance. We can- 
not but regard them with awe, as mysterious agents, whom 
the Almighty subjects, partially, to our will, but of whose es- 
sential nature we are ignorant. We know that they possess 
immense force, and though we seem to have them in some de- 
gree under our control, we are liable at any moment to be 
destroyed by their power. It is their Creator only, who knows 
the " hiding of their forces ;" — He only can restrain, and hold 
them in combinations so justly and wisely modified and balanced, 
as to maintain and preserve that beautiful harmony in the order 
of Nature and of Providence, which He has established. 



CHAPTER VII. 

CHEMICAL NOMENCLATURE. 

177. An important change of subjects now presents itself. 
The bodies we are about to examine, are such as we can either 
see, or handle, or can prove to possess weight ; they are, there- 
fore, known to be material, and are called ponderable, in distinc- 
tion from the class of agents called imponderable. 

178. The study of ponderable bodies naturally divides itself 
into two parts, called Inorganic and Organic Chemistry. By 

176. Concluding remarks. 

177. Meaning of the term ponderable. 

178. Distinction between Inorganic and Organic Chemistry. The same 
elements enter into the composition of Organic and Inorganic matter. 



CHEMICAL NOMENCLATURE. 71 

Inorganic Chemistry is meant the study of the elementary bodies, 
with their combinations, as existing in inorganized matter as 
water, air, earths, minerals, &c Organic Chemistry treats of 
the chemical constituents of plants and animals, but offers no 
elements not found in inorganic substances. It is owing to the 
different proportions, and mode of combination, that organic com- 
pounds differ in their qualities so essentially from compounds 
that are found in the inorganic kingdom ; thus the blood of ani- 
mals and the sap of vegetables, are peculiar fluids resulting from 
the action of a living principle, deprived of which, both animals 
and plants become the prey of the chemical and mechanical 
forces which are constantly in operation around them. 

179. Before proceeding farther it is necessary to explain the 
nature of certain bodies, to which we shall have frequent occasion 
to allude ; after which, will be given a brief exposition cf the 
principles and rules on which Chemical Nomenclature is founded. 
The important subject of Chemical affinity, will next be examin- 
ed, and the laws of chemical combination. These are necessary 
preliminaries to the consideration of the ponderable bodies. 
Though, at first, these subjects may seem obscure, the mists 
will gradually break away, and the science appear in its true 
and beautiful proportions ; — each advance then made, will reveal 
new and striking evidences of the immutable basis on which it 
rests ; convincing the student that Chemistry, if not itself a 
divine science, proclaims the divine origin of matter ; clearly 
refuting the absurd idea, that a blind chance, brought the ma- 
terial atoms into existence, and presides over their combinations. 

180. By the term salt, as used in Chemistry, is meant, a de- 
finite compound of an acid and a salifiable* base. 

An acid (see § 158,) is generally sour, soluble, capable of 
reddening the blue color of violets and of litmust, and of com- 
bining with and neutralizing the salifiable bases. But some 
acids are not soluble in water, and therefore do not taste sour 
nor redden vegetable blues ; others do not neutralize the salifi- 
able bases, though they combine with them. According to a 
strict chemical definition of the term, an acid is a substance 
which combines in definite proportions with salifiable bases to form 
salts. 

* Salifiable from the Latin Sal salt, with an English termination, means 
capable of becoming a salt. 

f Litmus is prepared from a lichen, (Lichen rocella ;) it is of a blue color, 
and paper dipped in its infusion furnishes a delicate chemical test. 

179. Preliminary subjects to be considered. 

180. Definition of a salt. Of an acid. Salifiable bases. Neutral, super 
and sub-salts. Soluble salts. Various properties of salts. 



72 SALIFIABLE BASES. 

Salifiable bases are all metallic oxides* except ammonia,f and 
the vegeto-alkalies.% All the soluble, salifiable bases, (including 
ammonia, but excluding the vegeto-alkalies,) have an acrid taste, 
and are highly caustic, turn to green, the blue of violets, restore 
the blue of litmus when it has been reddened by an acid, and 
combine with acids in definite proportions to form salts. 

These are the properties which constitute an alkali ; and hence the salifi- 
able bases which do not possess them all, are not called alkalies. But 
there is no proof that the absence of these properties in certain salifiable 
metallic oxides is not owing to insolubility. The insoluble, salifiable bases 
possess only the last mentioned and most important of the alkaline proper- 
ties, that of combination with acids. 

Some salts exhibit the properties of neither acid nor base, and are called 
neutral salts ; others are acidulous, which property generally arises from an 
excess of acid, but sometimes from the feebleness of the base; others are 
alkaline, generally from an additional quantity of the base, but sometimes 
from the weak neutralizing power of the acid. Acidulous salts are fre- 
quently called super salts, as super tartrate of potassa, &c; and salts ex- 
hibiting the properties of the alkaline base, are sometimes denominated 
s«6-salts, as sub-carbonate of soda. 

Some salts are soluble, others are not so; all soluble salts have taste, and 
most frequently a disagreeable one; none of them have odor, but the car- 
bonate of ammonia. Some are colored, others colorless, and many of them 
are capable of crystallization. 

181. If every substance, examined by the Chemist, were to 
be named as caprice or fancy might suggest, the memory would 
be capable of retaining but a very small number of the names. 
To obviate so great an inconvenience, a systematic nomencla- 
ture, expressive of the constitution of substances, was adopted 
by Lavoisier, Guyton-Morveau, and other French Chemists, 
about the year 1784. It is founded on the principle, that the 
name of every substance ought to express its composition, if a 
compound, or some striking property, if it be a simple body. 
The simple bodies already known, were permitted to retain 
their established names. 

In conformity with these principles, oxygen was named from 

* By metallic oxides is meant a compound substance composed of a metal 
and oxygen. Oxide of iron is oxygen and iron ; oxide of gold is oxygen and 
gold, «fcc. It is not to be understood that every metallic oxide is a salifiable 
base; some oxides are acids, and some neither acids nor bases. 

f Ammonia is a compound of two gases, Nitrogen and Hydrogen. 

% Vegeto-alkalies are compound alkaline bases, obtained in the analysis 
of Vegetable substance. 

181. On what principle is the systematic nomenclature founded ? Origin 
of the names of some of the elementary bodies. Names given to the com- 
binations of simple electro-negative bodies with other bodies. Names of 
combustions of simple combustible bodies with each other. Nomenclature 
of acids. Nomenclature of salts. More definite mode of describing salts 
than by the terms super and sub-salts. 



NOMENCLATURE. 73 

two Greek words, implying a generator of acids. Hydrogen 
literally means the generator of water. Chlorine signifies a green 
substance, &c. &c. The combinations of simple electro-nega- 
tive substances with other bodies are designated by names 
ending in ide, as oxides, chlorides, iodides, and bromides. And 
where these elements form more than one combination with the 
same body, the different compounds are distinguished by pre- 
fixing Greek ordinals, marking the relative proportions j as prot- 
oxide of iron, deuto-ch\oride of mercury, trito-io&ide &c, the 
highest compound being called per*-oxide, per-chloride, &c, 
meaning that the body has been oxidized, &c. through all the 
stages possible. The termination uret, is given to names of 
combinations of simple combustible bodies with each other : as 
sulphuret of lead, phosphuret of carbon, carburet of iron, tyc. 

Where but one acid is formed by the union of the same ele- 
ments, its name terminates in ic ; as muriatic acid, carbonic 
acid, &c. But it frequently happens that oxygen, by uniting 
in different proportions with the same body, forms several dis- 
tinct acids ; when this is the case, the acid highest in oxidation 
is distinguished by ic, and a lower one by ous ; and the inter- 
mediate degrees of oxidation are expressed by the prefix hypo, 
signifying under. Thus, sulphur forms with oxygen, the four 
following acids, viz ; sulphuric, hypo-sulphuric^, sulphurous, and 
hypo-sulphurous. 

The termination ate, expresses the salt of an acid, ending in 
ic § and the termination ite, the salt of an acid, ending in ous. 
Thus we have sulphates, and hypo-sulphates, sulphides and hypo- 
sulphites. 

It has been stated, (§180), that the same acid and base, by combining in 
different proportions may form different salts : and that the name -soper-salt 
is given to those containing more acid, and that of sa&-salt to those contain- 
ing more base than the neatral salt. These names are objectionable be- 
cause they do not express the proportions by which either ingredient is in 
excess ; so that different super-salts, or different sub-salts of the same base 
and acid are confounded under one general appellation. 

To obviate this inconvenience, the number of equivalents or combining 
proportions of acid in the super-salts is denoted by Latin prefixes ; while 
Greek numerals point out the proportions of base in the sub-salts. 

Thus we have the neutral oxalate, the binoxalate, and the quadroxalate of 
poiassa, the first of which contains one atom, the second two, and the last 
four atoms of oxalic acid to each atom of base. Again, among sub-salts 
are the neutral acetate, the di-acetate and the ^m-acetate of lead ; the first 
being composed of one equivalent of acid, and one of base, the second of 
one of acid and two of base, and the last, of one of acid to three of base ; 

* From the Latin per signifying through. 

f Hypo signifies under, or below, thus hypo sulphuric acid means one 
which has a lower degree of oxidation than sulphuric acid. 

7 



74 SPECIFIC GRAVITY. 

and if there were a fourth compound consisting of one of acid to four of base, 
it would be the tetra acetate of lead. 

182. The proportion of terms proto, deuto, trito, per, &c, when 
placed before the generic names of salts, refer not to the pro- 
portions of acid and base they contain, but to the degree of oxi- 
dation of the base. Thus the jmtfo-sulphate of iron means the 
sulphate of the protoxide of iron, the per-sulphate of copper is 
the sulphate of the per-oxide of copper, &c. 

Different salts may sometimes combine and produce what are called 
trifle salts, or, more properly double salts. A double salt may consist of two 
acids and one base, of two acids and two bases, or, what is by far the most 
common, of one acid and two bases. The latter are bi-basic salts ; such are 
the double tartrate of potassa and soda, which is the tartrate of potassa united 
with the tartrate of soda, commonly called Rochelle salt ; tartar emetic is 
the double tartrate of antimony and potassa. Sometimes, the name of one 
base precedes, and that of the other, follows the generic name ; as the 
ammonic-sulphate of copper, which is the double sulphate of copper and 
ammonia. 

183. Acids which are formed by the union of oxygen with 
another simple substance, are called oxacids, those composed of 
hydrogen and a radical are hydracids ; thus the proper chemical 
name of muriatic acid, (which consists of hydrogen and chlorine,) 
is hydro-chloric acid ; hydrogen and iodine form hydriodic acid ; 
and hydrogen with bromine constitutes hydro-bromic acid. 

Specific Gravity. 

184. The physical characters of bodies are often valuable aids in dis- 
criminating between different substances. Some of these characters, as the 
color, may be considerably affected by the presence of foreign substances. 
Among the most constant and valuable is specific gravity. 

The specific gravity of a substance is its weight, compared with an equal 
bulk of some other substance, taken as the standard of unity. This standard 
for solids and liquids is water, and for aeriform bodies, atmospheric air. If 
we weigh a solid body in air, and again wei?h it suspended in water, it will 
be found, in the last instance, to weigh less than in the first ; and the loss 
of weight is ascertained to be the exact weight of an equal volume of the 
fluid displaced : thus, it is an axiom in hydrostatics, that the weight which a 
body loses when immersed in a fluid is equal to that of an equal bulk of that 
fluid. 

If, therefore, a solid body be not soluble in water, we take its exact 
weight in the usual manner; then weigh it suspended in pure water, and 
subtract this weight from the former, — the difference is the weight of a bulk 
of water equal to the solid. We now have the proportion, as the difference 

182. The prefixes proto, deuto, &c, when placed before the generic name 
of the salts. Double salts. 

183. Oxacids and hydracids. 

184. Definition of the term specific gravity. Standard of specific gravity 
for solids and liquids. Mode of finding the specific gravity of a solid not 
soluble in water. 



SPECIFIC GRAVITY. 



75 



just mentioned, is to the weight of the solid in air, so is one, (the assumed 
specific gravity of water,) to a fourih proportional, which is the specific 
gravity required. 

185. The instrument used to determine the specific gravity of bodies is 
called the hydrostatic balance. BCD (fig. 45) is a balance; E a glass ves- 
sel containing water. Suppose we wish to determine the specific gravity 
of sulphur; we suspend a small bit, by a hair, or fine thread of silk, from 
the balance at C : we find it weighs in the air 12 grains. We then immerse 
it in the water as represented in the figure, and find it has lost weight : we 
add to the scale C, a sufficient number of grains to cause it to balance the 

Fig. 45. 




scale D. Suppose these grains are 6, this is then the weight lost by the 
immersion. We then say, as 6, (the difference between the bit of sulphur 
in water, and in air) is to 12, the weight in air so is 1, (the assumed speci- 
fic gravity of water) to 2, the specific gravity required ; or thus, as 6 : 12 : : 
1:2. 

186. If the solid, whose specific gravity you wish to find, is soluble in 
water but not in alcohol, ascertain first the specific gravity of alcohol and 
then take that of the solid with regard to alcohol just as before described. 
If the solid be soluble also in alcohol, any liquid in which it is insoluble 
may be substituted. 

187. To find the specific gravity of a liquid, fill any convenient phial with 
distilled water and ascertain its exact weight, taking care that it shall be 
perfectly dry on the outside ; then pouring out the water and drying the 



185. Hydrostatic balance. 

186. Mode of finding the specific gravity of a solid which is soluble in 
water. 

187. To find the specific gravity of a liquid. 



76 SPECIFIC GRAVITY. 

phial carefully, fill it with the liquid under examination and weigh it ; the 
last weight will be to the former as 1 is to the specific gravity of the liquid. 
Another mode consists in ascertaining the comparative heights of the 
columns of the two fluids which are necessary to support a given column 
of mercury ; the specific gravities of the liquids are in the inverse ratio 
of their respective columns. 

188. To ascertain the specific gravity of gas, it is first necessary to know 
that of atmospheric air. Sir George Shuckburgh states that 100 cubic 
inches of air weigh 30.5 grains and this estimate is generally adopted as 
correct. 

Having exhausted a thin glass flask by means of the air pump, it is to be 
filled with the °ras in question, and weighed. The proportion is exactly as 
in the case of liquids substituting the weight of an equal bulk of air for 
that of water. 

This is an exceedingly nice operation ; and the following circumstances 
must be strictly observed, — 

1st. The gas must be perfectly pure. 

2nd. It must be absolutely dry. Moist gas is dried by passing it over 
pieces of chloride of calcium, or of pure potassa, which absorb the moist- 
ure. 

3d. The influence of atmospheric pressure, in decreasing the bulk, con- 
sequently increasing the specific gravity of gases must be taken into ac- 
count. The average height of the barometric column is 30 inches ; if it 
should be more or less during the experiment, the apparent sp. gr. will be 
more or less than the true one. 

4th. As the bulk of a gas depends also on the temperature, if the ther- 
mometers of Fahrenheit do not stand during the experiment at 60°, the 
standard or mean temperature, a correction must be made upon the prin- 
ciple that gases expand by 1-180, of the bulk they occupied at 32°, for each 
additional degree of Fahrenheit's thermometer. 

189. It is a remarkable characteristic of chemical union that 
the compounds resulting- from it, for the most part, possess 
neither the external characters, nor the internal properties of 
their constituents. Thus, it is impossible to foretel from a 
knowledge of any two substances, what may be the nature of 
the body which will be formed by their combination. Chemistry 
requires, therefore, experiments, or trials, in order to prove, by 
every possible method, not only the nature of simple bodies, but 
the effects which may be produced by their union with each 
other. 

188. To find the specific gravity of gas. Circumstances to be regarded 
in weighing gases. 

189. Characteristics of chemical union. Why experiments are necessa- 
ry in chemistry. 



CHEMICAL AFFINITY. 77 

CHAPTER VIII. 

CHEMICAL AFFINITY. 

190. Chemical affinity is an attraction, which acts only at 
insensible distances, between particles of different kinds. The 
cause of affinity, is, at present, supposed to be, the same agent 
which produces galvanism and magnetism ; viz. electricity ; 
though other agents, as light and heat, modify the action of this 
primary cause. Affinity, is of three kinds, viz ; Simple, Elective, 
and double Elective Affinity. 

191. Simple Affinity is the union of substances without caus- 
ing any decomposition ; thus sulphuric acid added to soda, forms 
sulphate of soda, and potassa forms soap with oil and water. In 
these cases, no previous combinations are broken up. 

192. Experiments to show that affinity produces compounds whose properties 
differ, essentially, from those of the components. 

Exp. 1st. Common liquid Hydro-Chloric Acid consists of a gas dissolved 
in water ; it is very sour, inflames the skin and changes to red, the blue 
color of vegetable infusions ; these properties are derived from the gas it 
contains. Liquid ammonia, or spirits of hartshorn, is also a solution of a 
gas in water ; it possesses a well known pungent odor, acts as a caustic on 
the skin, and changes blue vegetable infusions to green. If drops of each 
of these liquids be spread with a feather on the bottoms of two glass vessels, 
the gases will escape from the water and rise. Now invert one of the ves- 
sels over the other, placing their mouths together, and they will both be- 
come filled with dense white vapor. After standing in the cold for a time, 
the vapor will condense on the sides of the vessel, forming a white crust, 
■which has none of the characteristics of either of the two constituents, and 
which, though solid, is composed of two gases; this is the common sal am- 
moniac, or muriate of ammonia. 

Exp. 2nd. Pour diluted nitric acid, or aqua-fortis, on some fragments of 
copper, a violent action, attended with much heat, will take place, suffocat- 
ing red fumes will rise,* and, at last, there will remain a bright blue liquid, 
which is a solution of nitrate of copper, and contains both of the materials 
used. 

Exp. 3d. Pour nitric acid, slightly diluted, on powdered tin. As in the 
last experiment, red fumes will be given off, and the tin will be converted 
into a white powder, which is a compound of oxygen and tin, oxide of tin. 

Exp. 4th. Pour strong sulphuric acid, into a strong solution of Hydro 
Chlorate of lime. The two transparent liquids will be converted almost 
instantly, with great evolution of heat, into a white solid, the sulphate of 
lime. 

* These fumes are very poisonous, if inhaled by breathing, and should be 
avoided. 

190. Definition of Affinity, its cause &c. Different kinds of affinity. 

191. Simple affiinity- 

192. Experiments to illustrate simple affinity. 

7* 



78 AFFINITY. 

Exp. 5th. Caustic soda is very acrid to the taste, and blisters the tongue. 
Dissolve some of this in Hydro-Chloric acid and boil to dryness ; and the 
result is common salt, Hydro-Chlorate of soda. 

193. A complete change of properties results from the chemi- 
cal union of bodies ; affecting their color, taste, odor and tem- 
perature ; causing them to pass from the solid, to the liquid or 
gaseous state, and vice versa ; and producing as great an altera- 
tion of their chemical, as of their physical characters ; so that 
we find it is impossible to judge beforehand, from the properties 
of two bodies, what will be the character of the compound they 
may form. 

194. In most instances of chemical action, the temperature is 
altered. Sometimes, as in a case where the action is attended 
with the liquefaction of a solid, or the vaporization of a liquid, 
the temperature falls. But, in most cases, an elevation of tem- 
perature takes place, as is exemplified in the foregoing experi- 
ments 2nd, 3d and 4th, and in the following ; — 

Exp. Mix a portion of strong sulphuric acid, with one fourth 
of its weight of water ; the liquid will become heated above the 
boiling point of water. In this, and many similar instances, the 
rise of temperature is attributable to a condensation and conse- 
quent diminution of volume, in the course of which some of the 
caloric of expansion is given off*, and accordingly the above 
mixture will be found to measure less than the two liquids did 
before mixing them. 

195. Change of properties affords a criterion by which it may 
generally be known whether chemical combination, or a mere 
mechanical mixture has taken place. 

There are a few cases in which the properties of one of the constituents 
are apparent in the compound. For example, the mixture of sulphuric 
acid and water, (see § 194,) still exhibits all the properties of sulphuric 
acid and will continue to do so, even when very largely diluted with water ; 
yet there can be no doubt that a chemical union exists between its two 
ingredients. 

Again, if common salt be put into water, it will begin to dissolve, and 
will in a short time, disappear entirely. The disappearance of the salt, is 
owing to its uniting chemically with the water, yet every drop of the liquid 
exhibits the properties of salt. In these cases, the combining energy of the 
bodies concerned is but small, and their union can be overcome by means 
proportion ably simple. 

196. It is an important law of affinity, that a substance is 
very differently attracted by other substances ; so, that, though 

193. General truths established by the preceding experiments. 

194. Temperature affected by chemical action. 

195. What fact is supposed to be proved by this change of properties ? 
Cases in which this change does not take place. 

196. Different degrees of affinity. 



SINGLE ELECTIVE AFFINITY. 79 

it may have a very strong affinity for one, it will have a very 
weak one for another ; and in some cases, there may be no affinity 
whatever, between two bodies j thus chalk and water may re- 
main together for any length of time, without combining. Some- 
times, in such cases, the union may be effected by the interven- 
tion of a third body, which may form, with one of the first, a 
compound capable of uniting with the other. For example, flint 
will not dissolve in water ; but if it be mixed with carbonate of 
potassa, and heated to redness in a crucible, a compound is 
formed which dissolves, readily, in water. 

197. Single Elective Affinity. In elective affinity, there is an 
election or choice, and, of course, an exclusion. If we present 
to a compound, a substance which has for one of its constituents 
a greater affinity than they have for each other, the old com- 
pound will be broken up, and a new one formed, leaving one of 
the constituents of the old compound disengaged ; thus, baryta 
has an affinity for hydro-chloric acid, and forms with it hydro- 
chlorate of baryta ; if, into its solution, sulphuric acid be poured, 
a white powder will fall to the bottom of the vessel. This is 
sulphate of laryta ; the compound having been formed, because 
baryta has a greater affinity for sulphuric, than for hydro-chloric 
acid. 

Exp. 1st. Camphor combines with alcohol, and forms a transparent solu- 
tion ; but on adding water, for which the alcohol has a greater affinity than 
for camphor, the latter is precipitated in the form of white scales. 

The following diagram illustrates this change : 



Alcohol and water. 



Solution ( Alcohol 

of 1 and 

Camphor. ( Camphor 



Camphor. 

The compound solution of camphor is represented at the left of the dia- 
gram. The interior of the figure, shows the constituent principles, (alcohol 
and camphor,) and at the right is the substance added, (water,) to produce 
a decomposition. Above and below are the results of this decomposition. 
The lower horizontal line is turned downwards in the center, to designate 
that the camphor is precipitated ; while the upper line, being straight, 
shows that the new compound, water and alcohol, remains in solution. 

Exp. 2nd. If sulphuric acid be added to carbonate of lime, sulphate of 
lime will be precipitated, and carbonic acid disengaged in the form of gas. 

198. Precipitation is of great use in Chemistry, separating solids from 
solutions in which they may be held, and reducing the molecules of a body 

1 97. What is implied by the term elective affinity ? Example. Exp. 
1st. Exp. 2nd. 

198. Precipitates. 



80 COMPLEX AFFINITY. 

to a state of separation, which cannot be attained by any mechanical divi- 
sion. Thus, precipitates possess their medical activity. They are also in 
a state favorable for entering into new combinations. For example, silex 
pulverized as fine as possible, may be boiled with liquid potassa without 
dissolving ; but when silex is precipitated from a chemical solution, it not 
only dissolves, readily, in solution of potassa, but yields to the action of 
some of the acids. 

199. Double Elective, or Complex Affinity takes place when 
two compound bodies, on being brought together, exchange their 
bases, and form new combinations. 

We will now compare the three kinds of chemical affinity : 

1st. Let the simple substance, A, be presented to the simple 
substance, B, if there is an affinity, they will combine and form 
a new compound ; this is a case of simple affinity. 

2nd. Let a simple substance, A, be presented to a compound 
one B C, and if A, have a stronger affinity for B than C has, the 
compound, B C, will be decomposed, and a new compound, A 
B, will be formed ; this is a case of single elective affinity. 

3d. If a compound, A B, be presented to another compound, 
C D, the old compounds may be broken up, and A, uniting with 
D, leaves B, to unite with C, forming the two new compounds, 
A C, and D B ; this is a case of double elective affinity. 

In single elective affinity, three substances are present, and two 
affinities in action ; while in complex affinity, four substances 
are present, and four affinities in action. 

200. Exp. Add to lime water a solution of sulphate of soda ; there is no 
decomposition, because the sulphuric acid of the sulphate, has a stronger 
affinity for soda, than for lime. If, instead of lime-water, we use Hydro- 
chloric acid, there is still no decomposition, because the soda, (of the sul- 
phate of soda,) has a stronger affinity for sulphuric, than for hydro-chloric 
acid. But let us take a compound of hydro-chloric acid and lime, (hydro- 
chlorate of lime) and mix this with the sulphate of soda, and a double de- 
composition will take place. The lime leaving the hydro-chloric acid, is 
attracted to the sulphuric acid, while the soda being disengaged, unites 
with the hydro-chloric acid. The tumbler which at first contained a liquid 
mixture of hydro-chlorate of lime, and sulphate of soda, now contains a 
solid precipitate, which is the sulphate of lime, (plaster of Paris,) over this 
solid stands a solution of hydro-chlorate of soda, or common salt, which is 
at once recognised by its taste. 

This experiment may be illustrated by the following diagram. 

Hydro-chlorate of Soda. 



Sulphate ( Soda Hydro-chloric acid } Hydro-cholrate 

of 1 and and > of 

Soda. ( Sulphuric acid. Lime. ) Lime. 



Sulphate of Lime. 



199. When Double Elective Affinity takes place. Examples of the three 
kinds of affinity. 

200. Exp. To shew the effects of complex affinity. 



AFFINITY. 81 

The original compounds appear on the right and left, without the brackets, 
while their constituent principles are near them, within the brackets. The 
new products are above and below the horizontal lines. The upper line 
being straight, indicates that the muriate of soda remains in solution, and 
the dip of the lower line, indicates that the sulphate of lime is precipitated . 

201. We here perceive a conflict of two series of attractions : 1st, those 
which tend to preserve the original compounds, and 2nd, those which tend 
to destroy those compounds, and to form new ones ; the former are termed 
quiescent affinities, the latter divelleni affinities. Double decomposition can 
take place, only when the divellent affinities are greater than the quiescent. 
Taking for example, the substances used in our last experiment, the affini- 
ties may be stated in numbers, thus. 

The attraction of lime for muriatic acid, 104 

Of soda for sulphuric acid, ....... 78 

Quiescent affinities, ...... 182 

Attraction of soda for muriatic acid, 115 

Of lime for sulphuric acid, ....... 71 

Divellent affinities, 186 

The original compounds are then held together by a force equal to 182, 
while the force which tends to draw these apart, and to form new com- 
pounds, is equivalent to 186, the latter, therefore, or the divellent affinity 
being the greater, overcomes the former or the quiescent affinity. 

202. Bergmann, of Sweden, first taught the doctrine of elective attraction. 
So much was he delighted with this wonderful law of nature, that he seemed 
not to observe how much affinity is modified by peculiar circumstances. 
Succeeding Chemists following his steps, seemed also to consider affinity as 
absolute and independent in its operations. Berthollet, a French Chemist 
of the present age, advanced some new opinions upon this subject. He con- 
sidered affinity as a mode of attraction, differing from gravitation only, in 
the subject upon which it operates, and that, in this respect, there is no 
real distinction between Chemistry and Natural Philosophy. Thus, accor- 
ding to the principles of Newton, the quantity of matter, must have an in- 
fluence upon combination ; and it is, therefore, by Berthollet, laid down as 
an axiom, that " affinity, is manifested by quantity of matter, or that the 
chemical action of a body, is exerted in the ratio of its affinity, and quantity 
of matter." It follows from this doctrine, that quantity of matter may com- 
pensate for feebleness of affinity. Its supporters, not content with showing, 
what every Chemist must admit, that chemical action is, in a degree, in- 
fluenced by quantity of matter, &c, endeavored to prove that there is, in 
fact, no such law in nature as affinity ; but that decompositions are caused 
by the circumstances that merely go to modify affinity. Sir Humphrey Davy 
opposed the innovations, of Bethollet, and showed that in many respects, his 
doctrine was false. 

203. The enlightened Chemist unites himself to no leader, to take for 

201. Quiescent and divellent affinities. In what case only double decom- 
position can take place. How illustrated by the last experiment ? 

202. Errors of Bergmann and others with respect to the unlimited power 
of elective attraction. 

203. Dangers of allowing prejudice to affect the mind in search of scientific 
truth. 



82 AFFINITY. 

granted all his opinions, and reject all which he does not approve. Even 
the young student, whose mind is unclouded by prejudice, is more likely to 
form correct opinions, upon the phenomena of nature, than that partial 
philosopher who has so long contemplated an object in one particular light, 
that he can see it in no other; or, who, delighted with some discovery of bis 
own, regards the whole fabric of science of less magnitude, than the one 
atom which he has added to it. 

204. Causes which modify Chemical Affinity. Chemical af- 
finity is so governed by fixed and immutable laws, that under 
the same circumstances, its effects will always be uniform, and 
although disturbing causes do often influence its operation, and 
modify its results, yet this no more disproves the existence of 
those laws, than the fact, that a body does not fall to the earth 
when suspended by a cord, disproves the existence of the laws 
of gravity. In either case, the force of attraction is all the time 
acting, but is counteracted by opposing forces. Indeed, we are 
acquainted with most of the disturbing causes, and with their 
mode of acting ; and, in many cases, are able, from this know- 
ledge, to predict what will be the variation from ordinary re- 
sults. 

205. The most important of the causes which modify affini- 
ty, are, cohesion, elasticity, quantity of matter, gravity and the ac- 
tion of the imponderables. 

206. Cohesion forbids freedom of motion among the particles, 
and prevents them from coming into that contiguity which is 
essential to chemical action. Two substances in the solid state, 
seldom act on each other, although they may have a strong ten- 
dency to do so. The most favorable state for combination, is 
the liquid one ; the particles have perfect freedom of motion, 
and if they do not combine, when in this condition, it is fairly 
inferred, that they have no affinity for each other. Caloric is 
frequently used to overcome cohesion, and to bring bodies into 
the liquid state, by fusing them. 

207. When a solid disappears in a liquid, without disturbing 
its transparency, it is said to dissolve ; the body which disap- 
pears is said to be soluble ; the liquid is called a solvent; the 
act of dissolving is called solution ; the liquid containing the dis- 
solved body, is also called a solution. When the body dissolved 
has changed its nature, and cannot be obtained in its original 
state by evaporation, it is said to be in a state of dissolution ; 

204. How far the laws of chemical affinity are fixed. The existence of 
these laws not disproved by a variation under peculiar circumstances. 

205. Some of the causes which modify affinity. 

206. Effect of cohesion upon chemical affinity. State most favorable for 
combination. Modes of overcoming cohesion, for purposes of chemical 
combination. 

207. Solution. Difference between a solution and a dissolution. 



AFFINITY. 83 

thus, mercury dissolves in nitric acid, but when the fluid par- 
ticles are evaporated, we do not obtain mercury again, but the 
nitrate of mercury. The combination of the mercury and nitric 
acid, is an example of strong chemical affinity, the nitrate of 
mercury having no resemblance to either of its constituent parts. 
On the contrary, after evaporating a solution of common salt, 
we have the same substance as we dissolved. 

208. A solution, though transparent, need not necessarily be 
colorless. For example, blue vitriol gives a blue solution, which 
is yet transparent ; but the color of ink is occasioned by very 
minute particles of black, solid matter, mechanically suspended, 
not dissolved in the liquid. 

Exp. Add to common ink, some drops of nitric acid ; the ink becomes 
colorless ; add a little potash in solution, and the ink is again black. This 
experiment may be thus explained : — the coloring principle of the ink, which 
is a combination of gallic acid and iron, called the gallate of iron, is mechan- 
ically suspended in the liquid. When nitric acid is introduced, the iron 
having a greater affinity for it than for gallic acid, combines with it, form- 
ing nitrate af iron, and the coloring principle being now decomposed, the 
liquid is no longer black. On adding potash, the nitric acid withdraws itself 
from the iron and unites with the potash. The iron being now left disen- 
gaged, returns to the gallic acid, and the coloring principle, gallaU of iron, 
manifests its existence by the blackness of the liquid in which it is sus- 
pended. 

209. The property of dissolving, called solubility, is possess- 
ed by some bodies, in a much greater degree than by others. 
A body may be soluble in one menstruum,* and not in another ; 
almost any liquid, may for some particular purposes, be used as 
a solvent, but the most common solvents are water and alcohol. 

210. When a soluble body is put into its menstruum, it goes 
on dissolving, till a certain quantity has disappeared, after 
which the liquid can dissolve no more of the same body; it is 
then said to be saturated, and the solution so obtained, is a satu- 
rated solution. A solution saturated with one body, may still 
dissolve another. 

The point of saturation of the same solid and solvent, varies 
with the temperature ; in general, the quantity dissolved is in- 
creased by raising the temperature. 

211. Some bodies, of which common salt is an example, are no more so- 
luble in hot, than in cold water ; and there are a few, as lime, magnesia, 
&c, which are even less so. 

* A menstruum, signifies a solvent. 

208. The coloring principle in ink not in solution. Exp. 

209. Different degrees of solubility. 

210. A saturated solution. When saturation takes place. Effect of tem- 
perature in varying the point of saturation. 

211. Some bodies not more soluble in hot, than cold water. 



84/ NEUTRALIZATION AND EVAPORATION. 

212. Neutralization is the mutual destruction, or change of properties, 
■which sometimes takes place when two substances combine in certain pro- 
portions. 

213. It might be supposed that the solubilities of different bodies, were 
in direct proportion to their affinities for the solvent ; but this is not the 
case. Two bodies of equal affinities for water, may be differently affected 
by cohesion ; and, as cohesion is an obstacle to the operation of affinity, that 
will be least soluble which has most cohesion. The boiling point of a satu- 
rated solution is at present the standard of comparison ; for as the affinity 
of the dissolved body for the solvent, must necessarily oppose the escape of 
the latter in vapor, the boiling point will be higher as the affinity is greater. 
Accordingly, all saline solutions boil with more difficulty than the solvent 
alone. Sea water, for instance, has a higher boiling point than fresh water ; 
but, by boiling it in distillatory vessels, the water may be collected in a pure 
state, and the salts will be left behind in the vessel. 

214. Bodies in solution, may, generally, be obtained again in the solid 
state, by evaporating the solvent; for the volatility of the latter and the co- 
hesive attraction of the dissolved body, are more than sufficient to counter- 
act affinity. 

Evaporation is usually performed in open, shallow vessels, placed over a 
sand bath and kept moderately warm. When the operation is slowly, and 
uniformly conducted, the solid usually separates in the form of regular, 
geometrical figures called crystals. The process of the formation is called 
crystalization. When the evaporation has been carried far enough for 
crystalization to take place, the fact may be known by the solution becom- 
ing covered with a film or pellicle. Another test, is, to place a few drops 
of the solution on the cold surface of glass or some other polished substance, 
if, in such case, a solid is deposited the point of crystalization has been 
reached. The evaporating vessel should then be removed, and set aside in 
some secure, dry place to cool. 

215. The cohesion of insoluble bodies, may be overcome by /mion and 
vaporizing ; thus, brimstone, on being subjected to heat, passes first into a 
state of vapor, and then condenses into the four of sulphur, which, when ex- 
amined with a microscope is found to consist of small, crystaline grains. 
Bismuth and some other metals may be crystalized in the same manner. 

216. In opposing caloric to cohesion, in order to promote affinity we must 
not go so far as to bring bodies into the state of vapor ; for then their elasti- 
city, will tend to remove the particles from the sphere of their action upon 
each other. Sometimes indeed, two gases or vapors unite; but the aeriform 
state is generally unfa voi able to combination ; indeed, a compound of a fixed 
and a volatile body may be generally decomposed by heat, which increases 
the elasticity of the latter, as, when limestone, (carbonate of lime,) is heated 
strongly, the gaseous, carbonic acid flies off, and quicklime remains. Strong 
pressure, by bringing the particles nearer to each other, sometimes causes 
two gaseous bodies to unite. When one of the gases to be combined is in- 
flammable, the union may be effected by setting fire to the mixture, or by 



212. Neutralization. 

213. Solubility not always in proportion to affinity. Effect of cohesion 
with respect to solubility. 

214. Evaporation. Formation of crystals. Effect of a rapid evaporation 
upon the crystals. Various crystaline forms. 

215. How may the cohesion of insoluble bodies be destroyed? 

216. Effect of the elasticity of vapors. 



CHEMICAL AFFINITY. 85 

the electric spark ; in these cases, there is commonly a violent explosion, 
and it should only be done in strong vessels. 

^17. Experiment to show the effects of cohesion and elasticity on Chemical 
Affinity. 

Heat, as we have seen, (§ 216,) decomposes carbonate of lime ; but no de- 
gree of heat has yet been able to decompose carbonate of potassa; this cir- 
cumstance would lead us to infer, that the affinity of potassa for carbonic 
acid is greater than that of lime ; but, 

Exp. 1st. If limewater, (solution of lime,) be poured into solution of car- 
bonate of potassa, the insoluble carbonate of lime will fall as a white precipitate, 
and the potassa will remain in solution. This would seem to show that the 
affinity of lime for carbonic acid, is greater than that of potassa. But, in 
this case, it is supposed that the cohesion of the carbonate of lime, co-opera- 
ting with the affinity of lime for the gaseous carbonic acid, effects the decom- 
position in opposition to the real order of affinities. 

Exp. 2nd. If solutions of hydro-cholrate of lime and carbonate of ammonia 
be mixed, there will be a double decomposition ; carbonate of lime will be 
precipitated, and hydro-chlorate of ammonia will remain in solution. 

Exp. 3d. Mix hydro-chlorate of ammonia and carbonate of lime in the solid 
and dry state, place the mixture in a long necked vessel, and apply heat to 
it, the decomposition will now be the reverse of that which takes place in 
the preceding experiment. Carbonate of ammonia will rise in vapor, and be 
condensed in the cool part of the apparatus, while hydro-chlorate of lime 
will remain in mass at the bottom. 

Each of the acids used in the last two experiments, has affinities for both 
the lime and the ammonia ; the preponderance of one pair of those affinities 
over the other pair, is determined, in Ex. 2, by the cohesion of the carbonate 
of lime, and in Ex. 3, by the volatility of the carbonate of ammonia. Gen- 
erally, when the affinity would admit of the formation of several modes of 
arrangement, one of which would produce an insoluble compound, (as the 
carbonate of lime for example,) that compound would be formed in prefer- 
ence to the rest, provided the materials are used in solution. But if the 
materials be in the dry state, and the operation be performed with the aid 
of heat, elasticity will determine the formation of a volatile compound, if 
such an one be among those which the substances present are capable of 
producing. 

218. In respect to quantity of matter as modifying affinity, it may be re- 
marked that there are some cases where the use of a large excess of one 
substance, enables us to decompose another contrary to the established or- 
der of affinities ; the decomposition, however, is seldom complete. 

219. Gravity sometimes interferes with chemical union, by causing the 
heavier body to sink, and thus be removed out of the sphere of the other's 



217. Circumstance which shows the affinity of potassa for carbonic acid, 
to be greater than that of lime for the same acid. 

Experiment showing that cohesion, combining with a weaker affinity may 
effect decomposition. 

Substances which result from the mixture of solutions of muriate of lime 
and carbonate of ammonia. 

Effect of mixing dry muriate of ammonia and carbonate of lime. Expla- 
nation of the changes which take place in experiments 2d and 3d. 

218. Effects of using a large excess of one substance in producing decom- 
position. 

219. Effects of gravity on chemical action. 

8 



86 LAWS OF CHEMICAL COMBINATION. 

action. The effects of gravity are illustrated, in the fusing together of two 
metals of different specific weights; the alloy being cast into an ingot, dif- 
ferent portions of it will be found to be unlike in composition ; the part 
which was lowest in the mould, will contain a greater proportion of the 
heavier metal than the other end. The interference of gravity, is obviated 
by agitation and by stirring. 

220. The effects of heat and galvanism, in producing decomposition have 
been noticed under the heads of the imponderables; we may farther observe, 
that the electric spark sometimes decomposes a compound gas through which 
it passes, and sometimes causes the union of two gases ; in the latter case, 
there is usually an explosion. These effects are commonly attributed to the 
htat of the electric fluid. 

LAWS OF CHEMICAL COMBINATION. 

221. Some substances unite in indefinite proportions, as when 
we mix water and alcohol, water and sulphuric acid &c ; though 
but a drop of one be mixed with a very large quantity of the 
other, every drop of the resulting mixture will contain propor- 
tions of both. 

In such mixtures, there is, at first, an evolution of heat, sometimes, (as 
in the case of sulphuric acid and water,) very considerable : and when the 
mixture has become cool, its bulk will be less than that of the two liquids 
before mingling them. 

222. Another set of bodies, unite in all proportions up to a 
certain point, beyond which no combination takes place. Exam- 
ples of this, are the solutions of salts in water, alcohol, &c, when 
any quantity of the salt not greater than that necessary to satu- 
rate the solvent, will be dissolved. 

In compounds of these two kinds, the affinities of the components are 
comparatively feeble ; neutralization does not take place, for the properties 
of all the substances concerned are quite apparent; and the combination is 
destroyed by comparatively feeble means, as evaporation and the like. But 
these kinds of compounds are highly useful and important, as by their means 
we are enabled to present bodies to each other, under the circumstances 
most favorable to action. 

223. There is a third class of combinations, far more numer- 
ous as well as interesting, than the other two. They are those 
in which the proportions of the constituents are regulated, by certain 
fixed and invariable laws. In such compounds, the affinities of 
the elements are more energetic, than in the two former classes ; 
the number of combining proportions of the same bodies is small, 
never, so far as is yet known, exceeding six ; and the elements 
neutralize each other. 

220. Effects of the imponderables, especially the electric spark, in pro- 
ducing decomposition and combination. 

221. Bodies which unite in indefinite proportions. 

222. Bodies which unite in indefinite proportions up to a certain point. 

223. Combinations where the proportions are always definite. 



LAWS OF CHEMICAL COMBINATION. 87 

224. 1st. Law of combination. Certain bodies combine in only 
one proportion. Thus chlorine and hydrogen, unite in the propor- 
tions of 36 parts, by weight, of the former, to 1 of the latter, and 
there is no method known of bringing them into combination, in 
any other proportions ; for if we mix 36 parts of chlorine gas, 
with 2 parts of hydrogen, there will, always, be 1 part of hydro- 
gen remaining imcombined ; or if we mix 72 parts of chlorine 
and 1 of hydrogen, only the proportions first stated will combine, 
the additional 36 parts of chlorine remaining in a separate state. 

225. 2nd. Law of combination. When any two elements com- 
bine in more than one proportion, the larger quantities of one are 
multiples by 2, 3, 4, or 5, of the smallest quantity of the other. 
Oxygen and hydrogen, form two compounds with each other j the 
first is 

Water, composed of hydrogen 1 part -J- oxygen 8 parts 

Deutoxide (or binoxide of hydrogen) 1 " -f- " 16 " 
Nitrogen and oxygen unite in five different proportions, form- 
ing compounds whose names and composition are as follows : 

Name. Parts of Nitrogen. Parts of Oxygen. 

Protoxide of Nitrogen, contains 14 for every 8=8x1 

Deutoxide of " " 14 " 16=8x2 

Hypo-nitrous acid " 14 " 24=8x3 

Nitrous acid " 14 " 32=8x4 

Nitric acid " 14 " 40=8x5 

No other compounds of the above elements are known : and 
if oxygen and nitrogen be mixed in any other proportions, one 
or more of the above named bodies, would be the result, but no 
intermediate compound. 

226. To the second law of multiples, there are a few apparent exceptions ; 
thus iron and oxygen combine in two proportions, which are 28 parts of iron 
to 8 oxygen, and 28 iron to 12 oxygen: the first quantity of oxygen being to 
the second as 1 to 1 1-2. 

Lead has three oxides, of which the composition is, 

Protoxide Lead 104 Oxygen 8=8X1 

Deutoxide 104 12=8x1 1-2 

Peroxide 104 16=8x2 

But examples of this kind, are not sufficiently numerous to overthrow the 
general rule ; and they can all be explained by the following hypotheses; 

1st. We may suppose that the apparent anomaly, results from our not 
being acquainted with all the combinations of the same two bodies. Thus, 
if we should hereafter discover the existence of a compound containing 28 
parts of iron to 4 of oxygen the oxides of iron would then accord with the 
law of multiples, viz., 

224. 1st. Law of combination. 

225. 2nd. Law of combination or law of multiples. The law of multi- 
ples illustrated in the compounds of nitrogen and oxygen. 

226. Apparent exceptions to the law of multiples. Suppositions on which 
the apparent anomalies in chemical combinations may be explained. 



88 LAWS OF CHEMICAL COMBINATION. 





Iron. 


Oxygen. 


1st, oxide 


28 (this is the supposed oxide.) 


4=4X1 


2nd, " 


28 


8=4X2 


3d, « 


28 


12=4X3 



The same reasoning would apply to the oxides of lead, and to other like 
cases ; and it is in accordance with facts which have already been discov- 
ered. 

2nd. We may suppose the anomalous compound to be formed, not by the 
direct combination of the two elementary substances, but by the union of two 
or more of the other compounds of those elements. Thus the first and last 
oxide of lead, might combine as follows, 

Lead. Oxygen. 

Protoxide 104 8 

Peroxide 104 16 

producing a compound 208 24 

where the lead and oxygen are in the exact ratio of 104 to 12, that is, in the 
same ratio as in the compound now called deutoxide of lead. This latter 
may be, therefore, not a distinct oxide, but a compound of two oxides ; 
which in that case would not furnish an exception to the law of multiples. 
This mode of explanation not only applies to exceptions in the third class of 
combination, (see § 223,) but to the whole of the first and second classes ; 
where the apparent great diversity of proportions, may be occasioned merely 
by the combinations of five or six definite compounds. 

227. 3d. Law of combination. The quantities of two bodies 
which respectively combine with a given quantity of a third 
body, are the precise quantities in which the first two combine 
with each other ; and these are also, the quantities in which 
they would unite with a fourth body. Thus 36 parts of chlorine 
combine with 8 of oxygen, to form protoxide of chlorine ; and 36 
parts of chlorine combine with 1 of hydrogen, to form muriatic 
acid (called hydro-chloric acid) ; now 8 of oxygen and 1 of hy- 
drogen are precisely the proportions of those two bodies neces- 
sary for their combining to form water. 

228. Bodies that unite according to proportional numbers, and 
the numbers expressing the combining proportions, are called 
proportionals, or equivalents. 

229. By analyzing several compounds of a particular body, and reducing 
the numbers expressing the proportions of the constituents to their lowest 
terms, the combining proportions, or equivalent of that body is established. 
And if we do this for a great number of different substances, referring, al- 
ways, the number determined to some particular standard, a scale of chem- 



227. 3d. Law of combination. 

228. Proportionals and Equivalents. Different senses in which the word 
equivalent is used. 

229. How may the combining proportions of a body be ascertained? Scale 
of chemical Equivalents, how established ? What substance is taken as the 
standard of unity in the scale of equivalents most commonly used, and what 
are the combining numbers of some simple bodies in relation to this stan- 
dard 1 



DISCOVERY OF THE LAWS OF COMBINATION. 89 

ical equivalents is determined, which greatly facilitates the operations of the 
laboratory. Such a scale has been established by Chemists. It is of no 
importance what number is taken as the basis of the scale, nor what sub- 
stance is the standard of unity, provided the proportions be duly observed. 
In the scale most in use, hydrogen is taken as 1, and consequently, 

Oxvsen is 8 

Sulphur 16 

Chlorine 36 

Nitrogen 14 

Potassium 40 

Sodium 24* 

230. The operation of the laws of combination is not confined 
to the simple substances, but has an equal influence over com- 
pound bodies. Thus 40 parts of sulphuric acid, which neutral- 
ize 48 parts of potassa, combine with 32 parts of soda: the same 
acid combines with potassa and with soda in other proportions, 
namely, SO (=2X40) to 48 and 80 to 32 : so that the law of 
multiples, (see § 225,) likewise governs these combinations. 
The third law is equally uniform, (§ 227,) for the 48 of potassa 
and 32 of soda, which are equivalent to 40 of sulphuric acid, 
will also neutralize 54 of nitric acid, 37 of muriatic acid, &c. 

231. The equivalents of compound bodies are foundby taking the 
sum of those of their constituents ; thus, sulphuric acid, contain- 
ing 1 equivalent of sulphur, 16, and 3 of oxygen, (3 times 8=24,) 
is 40 ; nitric acid consists of 1 equivalent of nitrogen, 14, and 
5 of oxygen, (5 times 8=40,) and its equivalent is 54. 

232. From the difference of the combining proportions of the acids and al- 
kalies, it follows that their neutralizing powers must differ; for it is evident 
that the greater this power, the smaller must be the quantity necessary to 
produce the effect. Thus the neutralizing power of soda is greater than 
that of potassa, in the inverse ratio of 48, the combining number of the lat- 
ter, to 32, the equivalent of the former. 

233. So well established are the laws of combination, and so sure is their 
operation, that it is very often possible to calculate the composition of a 

* In Dr. Thomson's scale of chemical equivalents, oxygen is employed as 
the basis and is assumed at 1, and therefore hydrogen must be 1-8 or, 125, 
sulphur 2, chlorine 4 1-2, &c. Dr. Wollaston, in his scale, calls oxygen 
10, Berzelius takes it at 100 ; but in all these scales the same proportions 
are observed. The system of numbers which makes hydrogen the unit or 
1 is generally preferred, as containing small numbers and few fractions. 



230. Compound bodies influenced by the laws of combination, and the 
law of multiples. 

231. How are the combining numbers of compound bodies found? 

232. Ratio of the neutralizing powers and combining proportions of acids 
and alkalies. 

233. What fact would lead to suspect an error in analysis ? 

8* 



90 ATOMIC THEORY. 

body before it is analyzed. And if the result of an analysis is at variance 
with these laws, it is a sufficient reason for suspecting error in the opera- 
tion, and for repeating our experiments. 

234. The discovery of these laws of combinations, is justly- 
considered as one of the most important events in the history of 
Chemistry. It has rescued the science from a chaos of confu- 
sion, and established it on the basis of certainty and demonstra- 
tion. For this discovery, science is indebted to the genius and 
industry of Mr. John Dalton of England. 

Atomic Theory. 

235. Before proceeding to treat of the theoretical explanation of the laws 
of combination, and the atomic theory, it will be necessary to caution the 
learner against confounding the one with the other. 1 he theory of Moms 
is founded on supposition : and however strong may be the arguments by 
which it is supported, it may possibly be, hereafter overthrown. Not so 
with the laws of combination. The proof of their existence is founded on 
multitudes of experiments, and is wholly free from speculation ; whether 
the atomic theory, therefore, be admitted or denied, the doctrine of laws of 
combination remains unshaken. 

236. This ingenious hypothesis was published by Mr. Dalton, to explain 
and account for the laws of combination which he discovered. This it does, 
on the assumption that all matter is composed of certain minute indivisible par- 
ticles, aggregated by attraction ; that the particles of the same kind of matter 
have the same form, size and weight : and that they are inconceivably smaller 
than any division of matter, which can be obtained by mechanical operations. 
The word atom, implying a thing so small that it cannot be further cut or 
divided, is frequently used to designate these supposed indivisible particles. 
Thf term molecule, is sometimes used in the same sense. 

237. This theory being granted, the laws of combination, which seem in- 
explicable on any other ground, would follow of course. For since chem- 
ical combination would take place between the atoms ; as, for instance, if 
a particle of water consists of one atom of oxygen, and one atom of hydro- 
gen, and the former atom weighs eight times as much as the latter, it is 
clear that any quantity of water must contain these bodies in the ratio of 8 
to 1. Again, since no addition could be made of either constituent in a 
less quantity than an atom ; that is, if A and B form any other compound 
than A B, it must be 1 A to 2 B, 1 A to 3 B, &c, or 2 A to 1 B, 3 A to 1 
B, &c. Thus one atom of oxygen to one atom of hydrogen, constitutes a 
particle of water, or protoxide of hydrogen, and two atoms of oxygen to one 
of hydrogen compose a particle of deutoxide of hydrogen; and as the oxygen 
is to the hydrogen, in water, as 8 to 1 ; so in the deutoxide of hydrogen, the 
compounds must be in the ratio of J6 to 1. Thus the law of multiples, is a 
necessary consequence of the atomic constitution of matter ; and this ne- 
cessity is as peremptory in the case of compound particles, as ia that of 
elementary atoms. 

234. Discovery of the laws of combination. 

235. Distinction between the Laws of combination and the atomic theory. 

236. How did Mr. Dalton attempt to explain the laws of combination ? 

237. How does the atomic theory explain the laws of combination and of 
multiples ? 



VOLUMIC THEORY. 91 

238. The terms Equivalents, combining proportions, &c, of bddies, are 
therefore only other names for the weights of atoms in comparison with the 
particular body which is chosen as the unit. 

239. Some years ago, it was a received axiom that matter is infinitely di- 
visible, and the question remained at rest till revived by Mr. Dalton. The 
preponderance of proof seems, now, on the side of the atomic theory; and 
the laws of combination alone appear sufficient to establish it.* 

The Volumic Theory. 

240. A curious law was discovered in 1808, by Gay Lussac, which gov- 
erns the proportions by measure, in which aeriform bodies combine. It ap- 
pears from his experiments, together with those of many other eminent 
Chemists, that when two gases or vapors, combine, it is in the ratio by 
volume of 1 to 1, 1 to 2, or some other simple ratio. Thus 1 volume of oxygen 
unites with two of hydrogen to form water ; 1 volume of vapor of sulphur with 
1 volume of hydro gen to torm sulphuretted hydrogen, 1 volume of nitrogen and 3 
volumes of hydrogen, form ammoniacal gas ; 1 volume of muriatic acid gas 
and 1 volume of ammonia, constitute muriate of ammonia. 

241. Further, from various considerations, it is inferred that the same 
law holds with regard to solid bodies which cannot be converted into va- 
pors by the action of heat; so that when such bodies enter into gaseous 
combinations, their vapors are in a simple ratio with those of the other con- 
stituents. Thus, carbonic acid is composed of 1 measure of the vapor of car- 
bon to 1 of oxygen gas. 

242. Gaseous bodies sometimes undergo a condensation in combining, 
and sometimes not ; but whenever a diminution of volume takes place, it 
likewise bears some definite and simple relation to the original bulk of the 
constituents, being one half, one third, &c. For example, no condensation 
takes place in the formation of muriatic acid gas, but one volume of chlo- 
rine and one of hydrogen form two volumes of the acid gas, on the other 
hand two measures of ammoniacal gas consist of one measure of nitrogen 
and three of hydrogen ; so that here the two simple gases in uniting, are 
condensed to one half. Again two measures of nitrogen and one of oxygen, 
form one of protoxide of nitrogen ; the condensation is, therefore, one third. 

243. Another curious result seems to flow from these facts. Water is 
considered as a compound of one atom of each of its constituents ; by expe- 
riment it is found that it contains two measures of hydrogen and one of oxy- 
gen. The protoxide of nitrogen, also consists of two volumes of nitrogen 

* Dr. Wollaston advocated the Atomic Theory in a very able disserta- 
tion upon the " Finite extent of the atmosphere," published in England 
in the Philosophical Transactions for 1822 ; and Professor Mitscherlich has 
treated of the same subject in his lucid observations upon the connections 
between the form and composition of bodies. 

238. By what terms are the weights of atoms designated ? 

239. The atomic theory not undisputed. 

240. Law of volumes discovered by Gay Lussac. Explanation of this 
law. 

241. Solids supposed to be subject to this law. Examples. 

242. Condensation of gaseous bodies explained in reference to the volu- 
mic theory. 

243. The volume of an atom of oxygen compared to the atoms of hydro- 
gen and nitrogen. 



92 VOLUMIC THEORY. 

and one of oxygen ; it contains, nevertheless, one atom of each. It there- 
fore follows, that the atom of oxygen is but half as large as the atoms of 
nitrogen and hydrogen. There are several other bodies, whose combining 
proportions, like that of oxygen is represented by half a volume; but for the 
greater part of substances, a volume and an equivalent are synonymous. 

244. It is evident that the laws of comhination by weight, and those 
which govern the proportion by volume must depend on the same circum- 
stances, the atomic constitution of matter. There is, however, one striking 
distinction between them. The proportions by weight in which two bodies 
unite, have no very remarkable dependence on each other. For example, 
6 parts of atoms of carbon and 8 of oxygen form carbonic oxide ; now 6 is 
not to 8 in any simple ratio. The proportions by weight exist between the 
different quantities of the same body that combine successively with a given 
quantity of another hody. But hy the law of volumes, not only is there the 
dependence just referred to, but also an evident relation between the bulks 
of the two substances. 



244. On what must combinations by weight, and by volume depend ? 
Distinctions between the two cases. 



END OF PART FIRST. 



PART II. 

CHAPTER IX. 



CHEMICAL CLASSIFICATIONS. DIVISION OF PONDERABLES. OXYGEN. 

245. By chemical analysis ponderable bodies are reduced to 
their ultimate elements ; these are divided into, 

1st. Non-Metallic, 
Id. Metallic. 

246. The electro-chemical theory furnishes a convenient system 
of classification. The Non Metallic elements are divided in two 
classes, according to their electrical affinities ; those which are 
attracted to the positive pole, possess the opposite or negative 
electricity, and are called electro-negative. Those which are at- 
tracted to the negative pole, possess the opposite or positive elec- 
tricity, and are called electro-positive. 

1st. Class. 2rf. Class. 

5 .j ( Hydrogen 



Oxygen 

Chlorine 

Bromine 

Iodine 

Fluorine 



§ P3 



Nitrogen 

Carbon 

Boron 

Silicon 

Phosphorus 

Sulphur 

Selenium. 



There are 42 metals, all of which are electro-positive. 

247. The Electro-negatives combine with the electro-positives ; 
the former are called supporters of combustion / the latter com- 
bustibles. 

The electro-negative substances unite, also, with each other ; and, in this 
case, one of them is negative and the other positive. Such combinations, 
however, are extremely feeble, and their elements are, consequently, easily 
disunited ; but the facility of their decomposition causes them to act with 
great energy upon other bodies. 

245. Division of elementary bodies. 

246. System of classification. Division of non-mefaZZic bodies. Number, 
and electrical character of the metals ? 

247. Supporters of combustion and combustibles. Combinations of the 
electro-negative substances with each other. 



94 



OXYGEN GAS. 



OXYGEN.* 



24*8. 



*H*.$,1 



Sp. gr. 



1. Air=\. 
16. Hyd.= \. 

The simplest form under which we are acquainted with oxy- 
gen is, that of a gas : in which state, like all other gases, it is 
conceived to be a compound of a solid, ponderable basis, with 
caloric, and, perhaps, with light and electricity. 

Oxygen was discovered by Dr. Priestly in 1774 ; a discovery 
which was the cause of very important changes in the state of 
chemical science. It has been called dephlogisticated air, empy- 
real air, and vital air. Lavoisier gave it the name of Oxygen, 
supposing it to be the only acidifier in nature and it retains & the 
name, though it is now known that there are some acids which 
contain no oxygen, and that many of Me oxides have no acid pro- 
perties. 

249. Mode of obtaining Oxygen Gas. Most of the oxides are decomposed 
by red heat ; and if the operation be performed in proper vessels, the ex- 
pelled oxygen gas may be collected. Red Lead, which is the deutoxide of 
lead, yields oxygen when heated to redness in an iron retort; by this loss of 
oxygen it is reduced to a protoxide. Red oxide of mercury, treated in the 
same way, is resolved into oxygen and metallic mercury ; nitrate of potassa, 
(nitre or salt-petre,) kept at a dull red heat in an iron or earthen retort, 
yields oxygen gas in considerable quantities. The residue is hypo-nitrite of 
Potassa. This mode is dangerous without a cautious regulation of the heat. 

Fi<* 46 a 

A, represents a furnace in 

which is placed the retort 

B, containing the substance 
which is to furnish the gas. 

C, is the pneumatic cistern 
(Fig. 46.) or water tube, 

D, the bell-glass receiver, 
E F, a shelf in the cistern 
on which the receiver be- 
ing filled with water and in- 
verted, is placed. The wa- 
ter in the cistern rises a few 
inches above the shelf, so that 
the water in the receiver is 

supported by atmospheric pressure. The gas issuing from the retort passes 
through a bent tube, and is conducted by it under the shelf, into the mouth 

* From the Greek oxus, acid, and gennao, to generate. The German 
Chemists call it sauerstoff, which, literally signifies sour stuff. 




248. Equivalents and sp. gr. of oxygen. State in which we are acquaint- 
ed with oxygen. Its discovery. Synonymes. The name founded in error. 

249. Substances from which oxygen may be obtained. Pneumatic cistern 
SfC Mode of obtaining oxygen. 



OXYGEN. 95 

of the receiver, and being lighter than water, it rises in bubbles and dis- 
places the water in the upper part. This process continues until all the 
water in the receiver has gradually disappeared, and the vessel is filled with 
oxygen gas. 

,250. The black oxide of manganese, when pulverized and heated in a re- 
tort, also furnishe's oxygen gas. From the state of peroxide, it is thus re- 
duced to that of deutoxide, losing about 128 cubic inches of oxygen for each 
ounce of the material. As this mineral often contains carbonate of lime 
which would introduce carbonic acid into the oxygen, it ought to be pre- 
viously purjywtl by digesting it with very dilute muriate or nitric acid. The 
same oxide yields twice as much oxygen, if after being purified, it is made 
into a paste»wlth sulphuric acid and heated in an earthen retort. In this 
case it is converted into protoxide of manganese, losing a whole equivalent 
of oxygen, instead of half a proportional as in the former case. The resi- 
due is Sulphate of Protoxide of Manganese : the sulphuric acid combining 
readily with this oxide of manganese, though it cannot with the deutoxide or 
peroxide. 

251. A process, eligible in small operations, but too expensive for large 
ones, is to heat chlorate ofpotassa in a green glass retort.* A spirit lamp is 
the best source of heat for this experiment. The salt may be made to 
yield, for each 124 grains, 48 grains or 141 cubic inches of oxygen gas; 
and there will remain in the retort 76 grains of chloride of potassium. The 
gas thus obtained is absolutely pure. In all these processes the gas may 
be collected over water. 

252. Properties. Oxygen gas is transparent and colorless ; 
and the least powerful refractor of light among the gases. It is 
said to emit light as well as heat, when suddenly and strongly 
compressed. It is tasteless and inodorous, a non-conductor of 
electricity, and is only very sparingly absorbed by water. It is 
the most perfect negative electric, having extensive and energetic 
chemical affinities, and combining with every elementary body 
without exception. It has neither acid nor alkaline properties, 
but some of its compounds are acids, some are salifiable bases j 
and some are neither acids, nor bases. Oxygen frequently com- 
bines in several proportions, with the same body, producing en- 
tirely distinct compounds ; and may even form with the same 
metal an acid, and a salifiable base — when this occurs, the acid 
is the compound which contains the greatest proportional quan- 
tity of oxygen. 

253. Oxidation may take place in two modes ; either slowly, 
in which case the progress of the chemical change is not percep- 
tible ; or rapidly, when heat and light are emitted, and the phe- 

* Green glass is preferable, because without great care, the more fusible 
white glass would be melted. 



250. Oxygen obtained from the black oxide of manganese. 

251. Oxygen from chlorate of potassa. 

252. Properties of oxygen. Its compounds. 

253. Two modes in which oxidation may take place. Rusting of metals. 
Combustion of wood, candles, &c. 



96 



COMBUSTION OF OXYGEN. 



nomena of combustion exhibited. Of the former, the gradual 
rusting of metals in the air, is an example ; while the combus- 
tion of wood, candles, &c, is an instance of the latter. 

254. It sometimes happens that a higher oxide of a particular body, is 
produced by rapid, rather than by slow oxidation ; but, on the other hand, 
the same compound may be formed by either mode. Thus the brilliant 
sparks that fly from iron on a smith's forge, and those struck from steel by 
a flint, are iron burning in the oxygen of the air ; and when cold these are 
found converted into the same oxide which is the basis of iron rust. 

The oxygen of the air, is the sole cause of its supporting combus- 
tion ; and, since this gas constitutes only \ part of the whole bulk of the 
atmosphere, it might be supposed that bodies which burn in air, would burn 
much more vividly in oxygen gas. 

Fig. 47. 




Exp. 1st. Let there be two bell glasses A and 2?, communicating with 
each other by a flexible leaden pipe, with a stop cock at C. Suppose A to 
be placed over a lighted candle on the plate D, which communicates with 
an air-pump plate as represented at E. It will be found that the candle 
will gradually burn dimly, and will at last go out, if no fresh supply be al- 
lowed to enter the bell-glass; if, on repeating the experiment, the air be 
withdrawn by means of the pump, the candle will be rapidly extinguished. 
It is therefore proved, that a candle will not burn in a vacuum, and that it 
can burn but for a short time in a small portion of atmospheric air. 

Let the experiment be repeated with the following change. Let the air 
be exhausted from both vessels, the stop cock C, remaining open, until the 
bell B, is filled with water from the pneumatic cistern. The stop cock 
being closed, fill the bell glass with oxygen gas. Now introduce a candle 
under the bell A, then having placed the bell again on the plate of the air- 
pump, exhaust the air, until the candle is nearly extinguished, and then open 



254. Effects of rapid and slow oxidation, 
combustion. Ex. 1st. 



Why the air is a supporter of 



OXYGEN. 97 

the stop cock so as to allow the oxygen from B, to enter. The candle will 
burn much more brilliantly, and for a longer time, than in the same portion 
of atmospheric air. 

Exp. 2nd. A slip of pine wood of the size of a match, ignited at one end, 
but not flaming, will be kindled instantly into flame, on being immersed in 
oxygen gas. 

Exp. 3d. A coil of fine iron wire, (Fig. Fig. 48. 

48.) burns in oxygen with beautiful scin- 
tillations. The wire must be tipped with 
sulphur, or some other combustible matter 
and ignited to commence the combustion. 
The globules of melted and burnt iron, if 
they fly against the bell glass, always break 
it ; and they have even been known to per- 
forate, and pass through it. 

Exp. 4th. Phosphorus burns in oxygen, 
with a light so dazzliDg, that the eye can 
scarcely contemplate it. 

255. After substances have burned for a 
time in oxygen gas, the combustion ceases ; 
in many cases the gas disappears, and if 
the operation be performed in a bell glass 
ever water, the latter fluid will be seen to 
rise in the vessel, to supply the place of_ 
the consumed oxygen. This is the case' 
when iron or phosphorus is used; for the; 
oxygen unites with the latter, producing* 
dense white fumes of phosphoric acid, which 
condenses upon the side of the vessel as the acid cools, or dissolves in the 
water ; for phosphoric acid, though it first appears as a vapor, is naturally 
a solid, soluble in water. When iron burns in oxygen, the black oxide of 
iron is formed, and takes at once the solid state. 

In some cases there is no apparent diminution of oxygen gas, because the 
new compound is gaseous ; thus sulphuric acid, and carbonic acid, produced 
respectively, by burning sulphur and charcoal in oxygen, are gases, of the 
same bulk, as the oxygen employed in forming them. But oxygen gas has 
nevertheless been consumed ; for on examining the residual gas, it will be 
found to exhibit an entirely new set of proporties, being in fact a new body, 
a compound of the combustibles with oxygen. Accordingly, no combustible 
will burn in it. 

256. Oxygen was formerly supposed to be the only supporter 
of combustion ; but, more recently, many other bodies are found 
to evolve light and heat, in combining with each other. This 
is particularly the case during the combustion of electro-positive 

Exp. 2nd. Exp. 3d. Exp. 4th. 

255. Why water will rise in the bell glass after oxygen has been consum- 
ed. Production of phosphoric acid. Formation of the oxide of iron. Why 
in some cases, there is no apparent diminution of oxygen gas. Production 
of sulphuric acid — of carbonic acid. 

256. Oxygen not the only supporter of combustion. Terms supporters 
of combustion and combustibles, to what classes of bodies applied ? Light 
and heat sometimes emitted by electro-positive bodies. The term combus- 
tion, how used at present ? 

9 




98 COMBUSTION. 

with electro-negative bodies ; and the teim, supporters of com- 
hustion has been applied to all the latter, as distinguishing them 
from the former, which are called combustibles. But light and 
heat are often emitted by two electro-positive bodies, while com- 
bining with each other, as in the case of iron and sulphur, and 
copper and sulphur ; so that the term supporters of combustion, 
can scarcely be regarded as proper, though, in accordance with 
custom, we may use it. The term combustion, also, is now used 
in a more enlarged sense than formerly, including not only, ra- 
pid oxidation, but all other cases of chemical combination in which 
heat and light are eliminated. 

257. One of the first who attempted to explain the cause of combustion, 
was Stahl, a German. He supposed that a certain substance, which he 
called phlogiston, (from the Greek phlogizo, to burn,) formed a part of all 
combustible bodies, and that, in every case of combustion, this inflammable 
principle was disengaged. Now, as a metallic wire, after burning in oxy- 
gen gas, is heavier than before combustion, it follows, that instead of hav- 
ing parted with something in the process of combustion, it has actually 
gained in weight. Therefore, instead of giving out this imaginary phlogis- 
ton, it is found to have united with oxygen. 

Lavoisier, finding that the new discovery of oxygen gas destroyed the 
phlogistic doctrine, published the tiheory that oxygen is the only supporter of 
combustion. On this supposition, he conceives that in all cases of combustion, 
the solid base of oxygen gas unites with the combustible body ; and that the 
light and heat of the oxygen, being thus set free, give rise to the phenomena 
of combustion ; from this theory it would follow, 1st, that the specific calo- 
ric of the new compound, is always less than the mean of those of the con- 
stituents. And, 2d, that all combustibles, in consuming the same quantity 
of oxygen gas, must give out the same quantity of light and heat. Now 
both of these conclusions are contrary to experience ; besides which, as be- 
fore stated, the fundamental proposition, that oxygen is the only supporter 
of combustion, is likewise untrue. So that the theory of Lavoisier, is liable 
to serious objections. But, as Dr. Turner justly remarks, " It is easier to 
perceive the fallacy of one doctrine, than to substitute another that shall be 
faultless." 

258. Substances which have been burned in oxygen, are no 
longer capable of combustion ; they are new bodies, having an 
entirely new set of properties. They have gained weight, and 
their increase is precisely equal to the oxygen consumed. Some 
bodies, on being heated after combustion, yield precisely the same 
quantity of oxygen which disappeared during the experiment, 
and thus return to their original condition. 

259. Respiration. Oxygen is the only gas which supports 
respiration, and it is owing to the presence of this gas, that ani- 

257. Stahl's theory of combustion. Lavoisier's theory. 

258. Change in substances which have been burnt in oxygen. 

259. Agency of oxygen gas in respiration. Exp. Showing the effect of 
oxygen upon the blood. How does oxygen affect the blood in respiration ? 
Arterial and venous blood. Change which takes place in the blood, in pas- 
sing through the lungs. 



RESPIRATION. 99 

mals can live in common air. Physiologists agree that its effect 
in supporting life, depends on its action upon the blood. If a 
portion of this fluid be drawn from a vein, it is perceived to have 
a dark color, approaching to black ; put it into a bell glass filled 
with oxygen gas, and it will very soon become florid red ; and 
the same change will ensue, though not quite so rapidly, if the 
blood be exposed to common air. The air in the jar being ex- 
amined, is found to have lost oxygen, and to have acquired an 
equal bulk of carbonic acid. 

This is precisely what takes place in respiration. The blood as it issues 
from the left cavity of the heart into the arteries, and is distributed by them 
through the system, is called arterial blood, and has the florid color. Having 
completed its circulation, it returns through the veins ; and here it is found 
to have acquired a larger quantity of carbon, and become dark colored; in 
this state it is called venous blood. Before it goes again into circulation, it 
passes through the spongy organ, called the lungs ; throughout which it is 
distributed in the countless microscopic tubes into which the veins have 
branched out, so as to expose the greatest possible surface. Here it comes 
in contact with the air with which the lungs have been inflated by the last 
inhalation ; the excess of carbon in the blood combines with oxygen, and 
forms carbonic acid gas, which is exhaled with the nitrogen of the air; the 
blood thus purified and rendered fit for circulation, passes on through the 
appropriate vessels to the left cavity of the heart, and is again distributed 
through the system. The air which is exhaled, having exchanged oxygen 
for carbonic acid, is no longer fit for supporting combustion and respiration ; 
and this is one of the reasons why crowded and strongly illuminated rooms, 
are unhealthy. 

260. But although oxygen gas is the sole supporter of respi- 
ration, it is too stimulating in its effects on the human system to 
be inhaled in an unmixed state. If inhaled in any considerable 
quantity, it produces fatal inflammation of the lungs. It is sup- 
posed that warm climates are beneficial to comsumptive persons, 
because the air being warmer, is less dense than in cold climates, 
and each inspiration, therefore, brings a smaller quantity of oxy- 
gen into contact with the lungs, which, in a debilitated state, are 
unable to bear the more oxygenated, and consequently more 
stimulating air, of a colder climate. 

One cause of the unhealthy effect of breathing the air of crowded rooms. 
260. Effect of breathing pure oxygen. Why persons with weak lungs 
require a warm climate. 



100 



CHLORINE. 



CHAPTER X. 



CHLORINE. 



261 



. Equiv. \ J/ 



vol. 100 
weight 36 



Sp. gr. 



25. Air=\. 
36. Hyd.= l. 



Chlorine gas was formerly called Oxymuriatic acid, from the belief that 
it was a compound of muriatic acid and oxygen. It was discovered by 
Scheele in 1774, who called it dephlogisticated marine acid. 
Fis?. 49. 

262. Chlorine gas may be obtained by mixing 
strong muriatic or hydro-chloric acid and per-oxide 
of manganese, and heating the mixture gently. 
An effervescence arises, owing to the escape of 
the gas, which may be collected in a bell glass (Fig. 
49.) over warm water; or the gas may be made to 
pass through a tube bent twice at right angles, a 
leg of which passes into a glass bottle. The gas, 
by its superior gravity, displaces the atmospheric 
air; when the bottle is full, which is known by the 
green color of the gas, it should be carefully closed. 
In this process, a portion of the hydro-chloric acid 
is decomposed ; its hydrogen combines with one 
atom of the oxygen of the manganese, and forms 
water y while the chlorine is disengaged. 

Another process for obtaining Chlorine is used when very large quantities 

are required. It consists in heating in a retort, A, (Fig. 50,) three parts 

of common salt (chloride of sodium) and one of peroxide of manganese, 

thoroughly mixed, and two parts of sulphuric acid, diluted with its own weight 

Fig. 50. of water. The lamp being placed 

tu der the retort, the mixture heats 
gradually, the chlorine gas being 
driven off, passes through the beak 
of the retort under the inverted bell 
j glass C, which is at first filled with 
yj water; as the gas rises, the water 
|j| subsides, until the whole receiver is 



filled with chlorine.. 
The chemical change 



in this ex- 



periment are as follows ; The svlphuric acid acting upon the solution of chlo- 
ride of sodium, disengages hydro-chloric acid ; the latter is decomposed by the 
peroxide of manganese (as explained in the former experiment) ; the sulphates 
of soda and manganese remain in the retort. 

263. Chlorine gas is of a green color, slightly yellowish, and 
derives its name from the Greek word which signifies green. It 



261. Equivalents and specific gravity of chlorine. Various synonymes. 

262. Mode of obtaining chlorine with muriatic acid and peroxide of manga- 
nese. Rationale of this process. Mode of obtaining chlorine with common 
salt and peroxide of manganese. Explanation. 

263. Some properties of chlorine. Effects of cold on chlorine gas. 



CHLORINE. 



101 



has an astringent taste, and a disagreeable, suffocating odor. It 
is exceedingly deleterious to the lungs, when inhaled, even though 
diluted with air. It is said to give out light, when suddenly- 
compressed with great force ; a property belonging to no other 
gases but oxygen and chlorine. A pressure of 4 atmospheres, 
(about 60 lbs to the square inch,) reduces it to a bright yellow 
liquid which resumes the gaseous form instantly, when the 
pressure is removed. 

Cold water dissolves about twice its bulk of chlorine, forming a solution 
which has the color, odor and general properties of the gas itself; and 
hence the necessity of heating the water over which chlorine gas is to be 
collected. If exposed to a temperature of 32° Fahrenheit, while mixed with 
watery vapor, it forms a solid hydrate* which appears in the form of crys- 
tals, on the sides of the bottle ; this hydrate is liquefied by the warmth of 
the hand. 

264-. Chemical character. Neither heat, light, electricity, nor 
galvanism has been able to decompose pure chlorine ; it is there- 
fore considered, a simple element. When chlorine is in a moist 
state, the watery vapor may be decomposed, the chlorine combin- 
ing with the hydrogen of the vapor, and the oxygen which form- 
Fig. 51. 




* A hydrate is a compound of water with another body, often in definite 
proportions. 



264. Why considered a simple element. Chlorine decomposes watery 
vapor in contact with it. Is an indirect oxidizing asent. 

9* 



102 CHLORINE. 

ed part of the same being liberated. As oxygen must be libera- 
ted whenever chlorine decomposes water, if an oxidable body be 
at the same time present, it will become oxidized ; so that chlo- 
rine is often an indirect, oxidizing agent, of great power. Chlo- 
rine supports the combustion of some bodies. 

265. A lighted candle being immersed in it, goes out after 
burning a short time, with a dull red flame. Phosphorus, and 
some of the metals, take fire spontaneously in this gas. In these 
cases, combination takes place between the burning body and 
chlorine, and the compound resulting is a chloride. 

Exp. The bell glass B, (Fig. 51.) represents the combustion of geld leaf 
in chlorine gas. The lower bell glass A, being filled with chlorine over the 
pneumatic cistern ; the upper bell glass is exhausted of air by means of an 
air pump, and the pipe which is connected with the apparatus. On turning 
the stop-cock between the two bell glasses, the gas from the lower one 
rushes up to fill the vacuum, and the gold leaf is immediately inflamed, and 
burns with great brilliancy, forming chloride of gold. 

266. As chlorine unites with simple bodies it cannot be an 
acid ; for acids combine only with metallic oxides, and not with 
the metals themselves. Besides, it has none of the other prop- 
erties of acids. It is the most intensely electro-negative body 
known except oxygen ; and is, consequently, always found at 
the positive pole, when a compound of it, with any other substance 
than oxygen, is decomposed by a galvanic battery. Its affinity 
for metals is even greater than that of oxygen ; so that if a me- 
tallic oxide is heated in chlorine gas, the oxygen is expelled, and 
a chloride of the metal is formed. 

267. Some of the chemical properties of chlorine render it ex- 
tensively useful in the arts of life. It destroys vegetable colors 
rapidly ; the bleaching appears to depend upon the decomposi- 
tion of water which must be present. The bleaching effect is 
supposed to be owing to the oxygen, liberated from the decom- 
posed water, chlorine performing only the part of an indirect, 
oxidizing agent. There are other facts in support of the same 
opinion, one of which is, that certain highly oxidized bodies, as 
duetoxide of hydrogen, and manganesic acid, are powerful bleach- 
ing agents. 

For bleaching, on a small scale, as in removing from linen and cotton, 
the stains of fruit or other vegetable substances, a solution of chlorine gas 
in water, may be used. But this solution in large quantities, gives off so 

265. Chlorine an imperfect supporter of combustion. Compound which 
results from the burning of a metal with chlorine. Exp. 

266. Proof that chlorine is not an acid. Its electrical affinity. Its af- 
finity for metals. 

267. Various uses of chlorine. Its bleaching properties. The particular 
office of chlorine in the bleaching process. Proofs that oxygen is the active 
agent. Experiment to prove the bleaching power of chlorine. 



CHLORINE. 103 

much gas as- to be deleterious to the workmen ; and the resulting hydro- 
chloric acid is injurious to the texture of cloth. Both, these inconveniences 
are avoided by using the chloride of lime, commonly known as bleaching 
powder. 

Exp. Immerse a piece of litmus paper, or of printed calico in a solution 
of chlorine, or of chloride of lime, or into a jar of the gas itself; (in the lat- 
ter case, the calico or paper must be moistened ;) the color will be discharg- 
ed in a short time. 

268. Chlorine destroys animal and vegetable poisons, wheth- 
er existing as miasma in the atmosphere, or in other forms. 

The air of a sick room is purified by sprinkling the floor with a solution 
of chloride of lime or of soda. The putrescence of meat is arrested, and 
taint removed by the same substances, which, likewise, in a dilute state, 
form an admirable wash for the mouth. Chlorine, in the gaseous state, and 
in solution in water, is a certain antidote for Prussic acid ; and it seems 
highly probable that the bite of a rattlesnake, or of a rabid animal would 
not be followed by such fearful consequences, if, as soon as they occur, the 
wounds could be dressed with a solution of this gas. 

It is not ascertained whether chlorine acts directly upon the 
poisonous matter, or Whether it is as in its bleaching property, 
an indirect, oxidizing agent. In either case, affinity for hydro- 
gen* is probably the cause of the phenomena. 

269. When chlorine is passed into a cold solution of a fixed alkali, it is 
absorbed in considerable quantity, and forms a compound which exhibits 
the odor, the bleaching effects, and the atiseptic properties of chlorine. (A 
disinfecting liquid, prepared by M. Labarraque, is a form of chloride of 
soda.) If this compound be heated, water is decomposed ; 5 atoms of chlo- 
rine, take 5 of hydrogen, and form 5 of hydro-chloric acid, which unite with 
5 of the alkali, forming a hydro-chlorate ; the 5 atoms of oxygen disengaged 
from the water, combine with 1 of chlorine, and constitute a particle of 
chloric acid, which also combines with 1 of alkali, and forms a chlorate. The 
solution thus contains nothing but two neutral salts, a hydro-chlorate and 
chlorate, and has no longer the distinguishing characters of chlorine. 

270. Chlorine is detected by its bleaching properties, and by 
producing, in a solution of nitrate of silver, a white precipitate, 
the chloride of silver, which soon becomes dark colored, on ex- 
posure to light. 

* Wherever we commence in our instructions in science, we must occa- 
sionally, refer to what is yet unexplained. This is peculiarly the case in 
Chemistry. The three most important of the elementary bodies, are Oxygen, 
Hydrogen, and Nitrogen ; they form combinations with all other known ele- 
ments. But in our system of arrangement, according to electro-chemical 
agencies, oxygen stands at the head of one division, and hydrogen at the head 
of another. We must therefore, in adhering to our arrangement, leave the 
consideration of hydrogen and nitrogen, till we have treated of the simple 
electro-negative bodies, though some of the latter are of much less impor- 
tance. 

268. Effect of chlorine upon animal or vegetable poisons. Practical ap- 
plications. Probable cause of its action upon poisonous matter. 

269. Disinfecting liquid, how prepared ? Effect of heating it. 

270. Tests of chlorine. 



104? CHLORINE AND OXYGEN. 

Compounds of Chlorine and Oxygen. 

271. These two important electro-negatives having for each 
other very weak affinities, cannot be made to unite by any direct 
method ; but, indirectly, we are able to produce several distinct 
compounds; the most striking characteristics of these combina- 
tions is the extreme facility with which they are decomposed, 
either by heat, or by the action of other substances. This is 
owing to the very weak affinity of chlorine and oxygen for each 
other. None of these compounds has ever been found in nature. 

272. Protoxide of chlorine 1 atom of chl. 36 to 1 ox. 8=44. 
Peroxide of chlorine 1 do chl. 36 to 4 ox. 32=68. 

The former of these compounds is sometimes called Hypo-chloroits acid, as 
also euchlorine, it being greener than chlorine. The peroxide is also called 
chlorous acid. The properties of these two substances may be advanta- 
geously studied by comparing them with each other. They are both gaseous, 
of a greenish-yellow color, and are copiously afltarbed by water, to which 
they communicate their color, odor and some of their chemical properties. 
They are highly explosive, and dangerous compounds : the protoxide ex- 
plodes by the heat of the hand, and the peroxide, at about the boiling heat 
of water. They bleach powerfully, but the protoxide reddens a vegetable- 
blue before it bleaches it, while the peroxide whitens it, at once. They in- 
flame phosphorus spontaneously ; explosion takes place, and the phosphorus 
continues to burn in the two component gases, forming a compound of each. 

273. Expansion is a necessary consequence of the decomposition of these 
gases ; for in each of them the two elementary gases are in a state of con- 
densation. In the protoxide, 4 measures of chlorine and 2 of oxygen, making 
6 measures, are so condensed by combination as to form but 5 measures of 
the oxide. In the peroxide, the contraction is still greater, for 4 measures 
of this gas contain 6 of the component gases, of which 2 are chlorine and 4 
are oxygen. The peroxide, therefore, explodes more violently than the pro- 
toxide. 

274. Chloric acid is obtained in solution, by adding sulphuric 
acid to a solution of chlorate of laryta. The insoluble sulphate 
of baryta is precipitated, pure chloric acid remains in solution, 
and may be obtained in a solid state, by evaporation. It was 
formerly called kyperoxy-muriatic acid, its salts are still called, 
by some, hyperoxy-muriates. 

275. Properties. Chloric acid combines with the alkaline 

271. Names and composition of the compounds of chlorine and oxygen. 
Their most striking character. These compounds not found native. 

272. What are the component parts, and chemical equivalents of the pro- 
toxide and peroxide of chlorine ? Comparison of these two substances with 
each other. Their properties. 

273. Why expansion is a consequence of the decomposition of the protox- 
ide and peroxide of chlorine. 

274. How is chloric acid obtained ? Synonyme. 

275. Properties. Names of its salts. Its effect on oxidable bodies. De- 
flagrating properties of its salts. Action of sulphuretted hydrogen with 
chloric acid. 



BROMINE. 105 

bases, forming salts, called chlorates. It readily affords oxygen 
to oxidable bodies, acting on them with great violence. The 
chlorates, have the same property, deflagrating with great vio- 
lence on hot coals, and producing a violent explosion when mixed 
with phosphorus or sulphur and struck with a hammer or heated. 
The explosion arises from the rapid oxidation of the combustible 
part of the mixture, at the expense of the chloric acid. Chloric 
acid is also decomposed by sulphuretted hydrogen, the hydrogen 
forming water with the oxygen of the acid, while the sulphur 
and the chlorine are set free. 

276. Perchloric Acid may be obtained by heating 1 part of water, 3 of sul- 
phuric acid, and 5 of perchlorate of potassa. White vapors arise in the 
receiver which become condensed into a liquid, on being mixed with sul- 
phuric acid, and distilled pure crystals, of perchloric acid appear. It is 
volatile, decomposable in heat at a higher temperature than that necessary 
to decompose chloric acid, and forms a class of salts, which, like the acid 
itself, deflagrate with combustibles. Its salts like the chlorates, are con- 
vertible by heat into oxygen and chlorides of metals. Perchloric acid is 
important, as affording the best method of distinguishing and separating po- 
tassa from soda ; for if it be poured into a solution containing these alkalies, 
or their salts, it precipitates the perchlorate of potassa, which is nearly in- 
soluble, while the perchlorate of soda is extremely soluble and remains in 
solution. 

277. The constituents of the two oxacids of chlorine are as follows; 

Chloric acid. 1 chl. 36, add 5 ox. 40=76. 
Per-chloric acid. 1 chl. 36, add 7 ox. 56=92. 



CHAPTER XI. 

ELECTRO-NEGATIVE SUBSTANCES. BROMINE, IODINE, FLUORINE. 

BROMINE. 

9.19, Vain,. S h V voL 10 ° I «„ ™ < 3 Water =1 

278. Equiv. I & wdght 75 I Sp. gr. j ^^ ^ >=1 

Bromine was discovered by M. Ballard, (of Montpelier, in 
France, about the beginning of 1826,) in sea-water and, on this 
account, was at first called muride ; after it was found to be 

276. Perchloric acid. 

277. What are the constituents of the two oxacids of chlorine ? 

278. Chemical equivalents and specific gravity of bromine. Its dis- 
covery, &c. 



106 BROMINE. 

nearly allied, in some of its characteristics, to chlorine and iodine, 
its name was changed to bromine (from the Greek bromos) signi- 
fying rank odor. It exists but in very minute quantities in 
sea-water, and has been found in the water of some mineral 
springs. In all cases, it is found, in nature, in combination with 
hydrogen, forming hydro-bromic acid, and united with potassa, 
or soda. 

279. In affinity for hydrogen bromine ranks next below chlorine; the lat- 
ter body, therefore, affords the means of procuring it in a separate state. 
In order to obtain it, sea-water is evaporated till all but the most deliques- 
cent and least crystallizable salts are deposited ; the residual liquid, called 
bittern* is then drawn off. Into this, chlorine gas is passed. The chlorine 
combines with the hydrogen and forms hydro-chloric acid, and thus the bro- 
mine of the hydro-bromic acid is set free. 

Bromine is very soluble in sulphuric ether ; therefore, in pouring some of 
this liquid into the decomposed bittern, an ethereal solution of bromine is 
formed, which being lighter than water, will float in a distinct stratum on 
the top, and can be poured off. The next step is to add potassa to the ether- 
eal solution ; bromide of potassium is formed, from which bromine is obtained 
by the addition of sulphuric acid and peroxide of manganese, for the same 
reason that chlorine is obtained by the same process, from chloride of sodium, 
(see § 262 ;) but bromine being a liquid, instead of a bell glass, (as in the 
case of chlorine,) we must attach a cold receiver to the neck of the retort. 

280. Physical properties. Bromine is very volatile giving off 
at common temperatures dense red vapors, when in an open 
vessel. 

Exp. Pour a few drops of liquid bromine into a glass flask, a beautiful 
vapor somewhat resembling that, of iodine will appear. 

It becomes congealed into a brittle solid at about 4° below 
zero. In mass, it is a blackish-red colored liquid like venous 
blood ; but in a thin stratum, especially when held to the light, 
it is of a bright hyacinth-red. Its vapor is acrid and corrosive. 
It is noxious when inhaled, and very poisonous when swallowed. 
A single drop upon the beak of a bird destroys life instantly. 

281. Chemical properties. Bromine is considered a simple 
body, having never been decomposed by the most powerful 
chemical agents. It is soluble in water, forming with it, at 32° 
a hydrate in red crystals. Its vapor extinguishes a candle, but 
supports the combustion of phosphorus, potassium and a few 
other substances, which take fire, spontaneously, and explode, in 
contact with liquid bromine. In all cases of combustion in bro- 

* Bittern is an uncrystallizable residue, after having extracted the com- 
mon salt from sea-water. It contains several deliquescent salts, among 
which is the hydriodate of soda. 

279. Mode of obtaining it through the agency of chlorine. Seoond mode 
of obtaining bromine. 

280. Physical properties. 

281. Chemical properties. 



IODINE. 107 

mine, a bromide of the burning body is found. Bromine possess- 
es bleaching properties ; to solution of starch it gives an orange 
color. A lighted taper burns for a few moments in its vapor, 
with a flame green at the base and red at the top. 

282. Compounds of bromine and oxygen ; — Bromic Acid is the 
only known compound, and has many of the properties of chloric 
acid. It consists of 1 equiv. of bromine, and 5 of oxygen j is de- 
composed by heat, and forms a class of salts, called bromates, 
which deflagrate with the more oxidable bodies. This acid is 
obtained by acting on bromate of baryta, with sulphuric acid. 

283. Bromine and Chlorine unite, (probably in the proportion of one atom 
of each,) to form the Chloride of bromine, a dense liquid, of a reddish yellow 
color, and very volatile, giving off acid and strongly odorous vapors. It 
dissolves freely in water, without decomposition ; the bleaching properties 
of the two constituents, still remaining in solution. Its vapors set some 
substances on fire, producing at once a chloride and a bromide of the com- 
bustible. 

IODINE. 

234. Equiv. \ b E jg, ™- \ Sp. gr. j 4 0W=1 

Iodine is a solid substance, of a bluish black color, resembling 
in its appearance, the cuttings of a lead pencil. It was discov- 
ered by M. Courtois of Paris, a manufacturer of salt-petre, in 18 12. 
He found that the residual liquor, after the preparation of soda 
from the ashes of sea weeds, had the property of corroding me- 
tallic vessels. On the application of sulphuric acid a dark co- 
lored substance was deposited which by the application of heat 
was changed into a violet colored vapor. He referred this phe- 
nomena to M. Clement, who described it as a newly discovered 
element. Gay Lussac in France, and Davy in England, soon ex- 
perimented upon it, and proved it to be a simple non-metallic, 
electro-negative substance, analogous to chlorine. The name 
iodine* was given from the beautiful violet color of its vapor. It 
fuses at 225°, and vaporizes at 347°. 

Exp. Put a few scales of iodine into a small glass flask, and hold it near 
the flame of a lamp. The solid will soon disappear, and the phial be filled 
with a vapor of a beautiful, violet eolor, and hence its name, iodine. As 
soon as the phial is removed from the lamp, the iodine is again seen in the 

* From the Greek iodus, violet colored. 

282. Bromine with oxygen. 

283. Bromine with chlorine. 

284. Equiv. and s p. gravity, of Iodine. History of its discovery. Origin 
of its name. Exp. 



108 



IODINE. 



solid form, and without any apparent change in its nature. The vapor of 
iodine is exceedingly heavy, having more than eight times the weight of air. 
If the vaporization be performed in a long tube or matrass, the vapor on 
reaching the cool part of the vessel, is condensed into minute, shining crys- 
tals. ° J 

285. Chemical Properties. Iodine is considered a simple body, 
because, like chlorine and bromine, it has never been decomposed. 
It requires 7000 times its weight of water to dissolve it, giving 
a slightly brownish-yellow solution. With alcohol and ether, 
it dissolves much more copiously, forming a deep brown solution. 
Although iodine, alone has a much higher vaporizing point than 
water, yet on account of the affinity of these two bodies, the 
aqueous solution of iodine, is distilled without separating them. 
Iodine acts powerfully on the animal system, as an irritant 
poison ; but in some diseases, it is employed medicinally, both 
externally and internally, in small doses, with great advantage. 
Iodine possesses strong affinities for the simple bodies, and weak 
ones, for oxides and other compound bodies. In general, what- 
ever combines with chlorine or bromine, will unite also with 
iodine, forming analogous compounds. 

286. Combinations of iodine with simple bodies are called 
Iodides. Some substances, when brought into contact with 
iodine, take fire, especially in open air; of these are phosphorus 
and potassium. 

Exp. Drop into a wine glass containing a few grains of iodine a small bit 
of phosphorus, immediate combustion will take place. 

Iodine destroys vegetable colors, but, instead of bleaching or 
whitening them, it usually changes them yellow. It leaves a 
yellow stain on the skin, which like that of bromine, gradually 
disappears, on account of the volatility of this substance. 

287. Tests. To detect free iodine, the color of its vapor and its odor, 
which is like that of muriatic acid, but less strong, are sufficient ; if, in com- 
bination, the iodine must be set free by chlorine, or by oxide of manganese 
and sulphuric acid. But in very minute proportions, iodine requires a more 
delicate test. A drop of the alcoholic solution of iodine added to a cold 
solution of starch will cause a beautiful blue iodide of starch to appear. An- 
other mode of testing the presence of this substance, is to dissolve a little 
starch in a solution of pure potassa and add this solution to the liquid sup- 
posed to contain iodine, and afterwards drop in a little sulphuric acid, if a 
blue compound appears, it is caused by iodine. 

288. Natural History. Iodine, exists in sea-water, by which 
it is also imparted to marine plants and animals. It is also 

285. Why is Iodine regarded as a simple body ? Its solubility. Effect 
on the animal system. Affinities. 

286. Iodides. Exp. Effect of iodine on vegetable colors and on the 
skin. 

287. Tests of iodine. 

288. Natural history from whence obtained. Uses. 



IODINE. 



109 



Fig. 52. 



found in the water of some mineral springs, it bears, however, 
a very small proportion to the other bodies with which it is mix- 
ed. Like chlorine and bromine, it is always in combination 
with hydrogen, constituting a hydracid, which is combined with 
a salifiable base. Sea water is believed to contain hydriodate of 
soda, or potassa, from which the iodine is extracted. Most of 
the iodine of commerce is obtained, from the impure carbonate 
of soda, called Kelp, which is merely the ashes of sea-weed. 
Great quantities are prepared on the coasts of Scotland. It is 
used for the goitre (a swelling of the neck) and other glandular 
diseases. 

289. Exp. Iodine may be obtained by add- 
ing sulphuric acid to bittern, and applying heat. 
A portion of the sulphuric acid takes the soda 
of the hydriodate of soda, and liberates ihehy- 
driodic acid. This reacts on the remaining 
sulphuric acid, the oxygen of the latter uniting 
with the hydrogen of the former to constitute 
water. The iodine of the hydriodic acid is 
thus disengaged, and the bittern becomes dark 
colored, on account of the free iodine. Let 
this liquid mass be now introduced into the re- 
tort a, (Fig. 52.) through the tubulure b ; on 
placing the retort over the flame of a lamp, 
the violet colored vapors of iodine fill the re- 
tort, and rising into the receiver c, are conden- 
sed. If the receiver be covered with a wet 
cloth, (as represented in the figure) it will as- 
sist in keeping it cool. The crystals of iodine 
are washed out of the receiver with a small 
quantity of water, and dried upon blotting pa- 
per which serves as a filter, the liquid passing 
through its pores, and the solid particles re- 
maining on its surface. 

290. Iodic Acid. 1 Iod. 124, to 5 ox. 40=164. This is of the 
same class with chloric, bromic and nitric acids. It is a solid 
body, very soluble in water and even deliquescent ; soluble in 
nitric and sulphuric acids, from which solvents it may be sepa- 
rated in crystals. It forms with the alkalies and other bases, a 
class of deflagrating salts called Iodates. 

The superior affinity of iodine for oxygen enables it to decompose the 
oxide of chlorine, and form iodic acid ; at the same time, the chlorine com- 
bines with another portion of iodine to form chloriodic acid. The latter body 
being exceedingly volatile, is easily separated by a gentle heat. Iodic acid 
is otherwise obtained by boiling iodine in nitric acid, by which means the 
latter is decomposed and furnishes oxygen to the former. 




289. Exp. Mode of obtaining iodine. 

290. Equiv. of iodic acid. Properties, 
acid. 

10 



Iodates. Formation of iodic 



110 FLUORINE. 

291. Iodous Acid, is another compound of oxygen and iodine, which is 
proved to exist, but has never been indisputably obtained in a free state. 
There is probably, still another oxide of iodine, containing even less oxygen 
than iodous acid. 

292. Chloriodic Acid. 1 Iod. 124, to 2 chl. 72=196. This is a combina- 
tion of chlorine and iodine, procured by passing chlorine gas into a dry bot- 
tle containing iodine. It is solid, of an orange yellow color, very volatile, 
very soluble in water, and deliquescent. Its solution is strongly acid ; but 
when an alkali is added, instead of forming a chloriodate, we obtain a hydro- 
chlorate and an iodate. This is owing to the decomposition of water ; the 
oxygen of which combines with iodine and the hydrogen with chlorine. 
The iodic and hydrochloric acids thus formed, take, each, its portion of the 
alkali. 

Bromine and iodine combine and form bromide of iodine. 

FLUORINE.* 

293. Fluorine has never been obtained in an uncombined state 
owing, as is supposed, to its very energetic affinities for other 
substances. It is one of the constituents of fiuor spar, from 
which the compounds of fluorine are commonly obtained. It is 
considered an electro-negative body, as possessing intense affi- 
nities for simple substances, and forming with hydrogen, an acid 
called hydrofluoric. 

294. Hydrofluoric Acid. This acid is obtained by heating a 
mixture of sulphuric acid and powdered fluor spar {fluoride of 
calcium). 

Figr. 53. 

Exp. The mixture must be made in a metal- 
lic retort, (Fig. 53.)(on account of the pecul- 
iar action of the acid on glass) and the vapor of 
nydrofluoric acid must be received in a close 
vessel c, of one of those metals. The vapor 
passing through the tube b into the receiver, 
which is kept cool, by ice or cloths wet in 
cold water, is condensed into a liquid. This 
is hydrofluoric acid, and must be preserved in 
a closely stopped metallic bottle. 

295. Hydrofluoric acid, in the liquid 

* Silliman justly remarks, that "it appears premature to place fluorine, a 
principle purely hypothetical, along side with chlorine and iodine, whose dis- 
tinct existence and peculiar energy are manifested in so many remarkable 

forms." 

291. Iodous acid. 

292. Composition of chloriodic acid. How procured? Properties. Bro- 
mide of iodine. 

293. Why is it supposed that fluorine has not been obtained in a separate 
state ? From what mineral are its compounds obtained ; supposed proper- 
ties of fluorine. 

294. How is hydrofluoric acid obtained ? Exp. 

295. Its affinity for water. Its effects on animal and vegetable bodies. 




FLUORINE. Ill 

state, is very volatile, giving off dense white fumes if exposed 
in an open vessel, at the temperature of 60° F. Its specific 
gravity when pure, is but little above that of water ; but when 
combined with some water, it forms a less volatile hydrate of the 
specific gravity of about 1. 25. This acid has an affinity for wa- 
ter, even much greater than that of sulphuric acid. In combining 
with water, it produces very great heat, and causes a hissing like 
that produced when hot iron is quenched. It corrodes animal 
and vegetable bodies more powerfully than any other substance, 
producing a deep and dangerous ulceration when it is put on 
the skin. This action is the result of the powerful affinity the 
acid has for water. 

296. It also acts on glass, dissolving the siliceous matter of 
that substance and destroying its transparency ; or even perfor- 
ating it when a sufficient quantity of acid is used. 

By this action, two compounds are formed ; the oxygen of the silex forms 
water with the hydrogen of the acid ; while the silicon unites with the 
fluorine to form a colorless acid gas, called fluosilicic acid. 

This property of hydrofluoric acid affords means of etching 
or engraving on glass. The glass must be covered with a thin 
and uniform coat of wax, after which a figure is traced on it with 
a sharp steel point. If it be now exposed to the fumes of the 
acid, or wet with the liquid acid the glass will be corroded 
where the wax has been removed by the steel point, while the 
covered parts will be left untouched. 

297. With oxides, hydrofluoric acid acts variously, combining with some 
to form hydrojluates, and decomposing others, in which case, water and a 
fluoride of the metal are the result. It is a powerful solvent, dissolving 
rock crystal, flint, and other siliceous matters, besides several other bodies 
which are not attacked even by nitro-muriatic acid. 

Sulphuric acid displaces this acid from any of the hydrofluates ; and then 
the hydrofluoric acid can be detected by exposing glass to the fumes as they 
rise. 

298. Some Chemists are disposed to regard this acid, (instead of fluorine 
and hydrogen,) as a compound of fluorine and oxygen, called fluoric acid ; 
and all phenomena relating to it are capable of explanation under this view. 
Thus fluor spar may be considered a fluate of lime instead of a. fluoride of 
calcium ; so that when sulphuric acid acts on this mineral, it may be sup- 
posed simply to combine with the lime and liberate fluoric acid. Some re- 
cent experiments, however, seem to yield conclusive evidence in favor of 
the first mentioned view of the subject, or, that the acid in question, is hy- 
dro-fluoric, consisting of fluorine and hydrogen. 

299. Fluoboric Acid was discovered by Gay Lussac and Thenard, in an 
experiment intended to prove that the acid we have described under the 

296. Action of hydro-fluoric acid on glass. Compounds formed by this 
action. Etching on glass. 

297. Action of this acid with oxides. lis solvent properties. Is displaced 
by sulphuric acid. 

298. Theory which considers this as fluoric rather than hydrofluoric acid. 



112 FLUOBORIC ACID. 

name of hydrofluoric acid is an oxacid. Boracic acid being a compound of 
boron and oxygen, they endeavored by its aid, to obtain fluoric acid from 
fluor spar. If they succeeded, it would establish their opinion on the dis- 
puted point ; for there being nothing present in the experiment but boracic 
acid and fluor spar, both anhydrous,* there could be no hydrogen in the pro- 
duct. 

But instead of hydrofluoric, (or fluoric,) acid they obtained a new gas, 
which does not act on glass ; is very soluble in water, which it attracts so 
strongly as to produce dense white fumes in the air when the least moisture 
is present ; and decomposes by water, forming boracic and hydrofluoric acids, 
borate of lime remaining in the retort. The discoverers believed that a por- 
tion of the boracic acid united to the lime and liberated fluoric acid; and 
that the latter immediately combined with another portion of boracic acid, 
to form the. fluoboric gas which is therefore a compound of the two acids. 

The decomposition of the fluoboric gas by water, and the consequent de- 
position of boracic acid, they attributed to the superior affinity of water for 
fluoric acid, by which the latter was taken from its combination with 
boracic acid. 

300. The chemical changes in this experiment appear to be as follows. — 
The two materials boracic acid and Jluor spar {fluoride of calcium) being mix- 
ed and heated strongly in an iron tube or retort, the oxygen of a portion of 
the boracic acid, combines with calcium, to form lime, fluorine combines with 
the boron, which has thus been deserted by oxygen, and forms the fluoboric 
gas ; and, finally the remaining boracic acid unites with the newly formed 
lime, and borate of lime remains in the retort. The fluoboric gas being a 
compound of the electro-negative fluorine with the electro-positive boron, 
when it is passed into water the fluid is decomposed ; its hydrogen unites 
with the fluorine, and its oxygen with the boron, forming thus, boracic and 
hydrofluoric acids, of which the latter is wholly dissolved, while much of the 
former is deposited. The moisture of the air effects the same decomposition 
of this gas, the fumes being rendered quite opake by the particles of solid 
boracic acid. On account of the formation of these fumes, fluoboric gas is 
of use in testing the minutest quantities of vapor in gases. The strong af- 
finity of this gas for water, enables it to char animal and vegetable bodies 
with their oxygen and hydrogen, thus developing their carbon. 

301. Fluoboric acid unites with alkalies forming salts called fluoborates. 
When potassium is heated in this acid, the fluorine combines with it, and 
boron is liberated ; the same decomposition occurs when potassium is heated 
with an alkaline fluoborate, which furnishes the best method for obtaining 
boron. This acid gas is always generated when boracic acid is brought into 
contact with hydrofluoric acid ; and, accordingly, an easier process for ob- 
taining it, than the one given, (see § 299,) is to mix those two bodies in a 
retort and apply heat. Or it may be obtained by heating a mixture of bo- 
racic acid, fluor spar and sulphuric acid. The gas should be collected over 
mercury. 

* Anhydrous signifies without any water, entirely dry. 

299. Discovery of fluoboric acid. Nature of the gas obtained by Gay 
Lussac and Thenard with boron and fluorine. Its attractions for water. 
Opinion of the discoverers of this gas respecting the changes which accom- 
pany its formation. 

300. Another explanation of the chemical changes in this experiment. 
Use of this gas as a test. Why it chars animal and vegetable bodies. 

301. Salts of this acid. Other modes of obtaining fluoboric acid. 



FLTJO-SILICIC ACID GAS. 113 

302. Fluo-silicic acid gas, is a compound concerning the nature of which 
the same question may be raised, as in the case of fluoboric gas. It is gen- 
erated when hydro-fluoric acid comes in contact with silex, and may either 
be composed of fluorine and silicon (in which case the oxygen of the silex 
unites with the hydrogen of the acid,) or, it may be considered, as a com- 
pound of fluoric acid and silica. We shall treat of it under the first suppo- 
sition. It may be obtained by mixing, in a retort, powdered fluor spar and fine 
sand, (or powdered glass, of which silex is a principal constituent,) and heat- 
ing with a lamp. The gas is to be collected over mercury. 

303. Properties of fluo-silicic acid gas. It is colorless and transparent, a 
non-supporter both of respiration and combustion, and forms dense white 
fumes in moist air. Its affinity for water, enables it to corrode the skin and 
to char vegetable matter. The fluorine in this gas being saturated with si- 
lex, it does not attack glass. It is soluble to a great extent in water, but is 
decomposed by it, with formation of hydrofluoric acid, and of silex which is 
deposited. The decomposition, however, is not total ; some silex remains 
in solution ; and constitutes with the hydrofluoric acid, what is generally 
considered a distinct compound and called hydro-fluosilicic acid. If the 
watery solution be filtered to remove the deposited silex and then evaporat- 
ed, the vapor of hydrofluoric acid is expelled, and the original gas is given 
oft' unaltered ; but if the evaporation be performed without filtration, the 
silex is redissolved, and the fluosilicic gas is reproduced. 

If this gas be passed into an alkaline solution the whole silex is deposited, 
and a hydrofluate of the alkali is formed. 

304. The acidity of fluosilicic, and of fluoboric gases is by some, consid- 
ered doubtful. It can only be exhibited with the aid of water, in which 
case decomposition takes place, and other acid compounds are formed, to 
which alone the acid reaction might be owing. Accordingly, some Chem- 
ists consider these gases as only the per fluorides of boron arid of silicon. 

The acid property, however, seems to be sufficiently established by the 
fact that these gases unite with gaseous ammonia and form solid compounds 
or salts. 

305. The hydro-fluosilicic acid unites with alkalies and other bases. Its 
combination with potassa is of difficult solubility, and therefore this acid is 
sometimes advantageously used to remove potassa from solutions. 

302. Nature of fluo-silicic acid gas disputed. When the gas is generated. 
Composition. How obtained? 

303. Properties. Formation of hydrofluosilicic acid. Effects of passing 
this gas into an alkaline solution. 

304. Arguments against, and in favor of the acid nature of fluosilicic and 
fluoboric acids. 

305. Affinities of hydrofluo-silicic acid. 

10* 



114 HYDROGEN. 

CHAPTER XII. 

SIMPLE ELECTRO-POSITIVE SUBSTANCES. (Not Metallic.) 

306. The Non-metallic, electro-positive, substances are, as fol- 
lows, viz : 

1 Hydrogen, 5 Silicon, 

2 Nitrogen, 6 Phosphorus, 

3 Carbon, 7 Sulphur, 

4 Boron, 8 Selenium. 
Hydrogen and nitrogen are gases : carbon, boron and silicon, 

are dark colored, insoluble and infusible powders, scarcely af- 
fected by acids, and forming weak acids by oxidation. Phos- 
phorus, sulphur and selenium are fusible, volatile, and combus- 
tible solids, producing strong acids by combinations with oxygen. 
They have affinities for the electro-negatives and are found at the 
negative pole where their compounds and those of the electro-ne- 
gatives are decomposed by galvanism. They have, also, more 
or less tendency to unite with each other, and several of this 
class combine with the metals. 

HYDROGEN. 

on - p . ( by vol. 100 ) ( 0, 694 J2ir=l 

mi.Eqmv. \y wdght x \ Sp.gr.^ Ryd=l 

Hydrogen is so named from the Greek hudor, water, and 
gennao, to generate, because it enters largely into the formation of 
water. It was formerly called inflammable air from its combus- 
tible nature and phlogiston, from the supposition that it was the 
matter of heat. It is one of the most important of all the inflam- 
mable substances ; existing in nature in a variety of combina- 
tions, and forming \ part by weight, of water. Though known 
for centuries before, Mr. Cavendish, in 1766, first ascertained 
the nature of this gas as a distinct elementary substance, and 
experimented upon its properties. 

308. Hydrogen is obtained by the decomposition of water, 
which may be effected in several ways. 

306. How are the Electro-positive substances divided ? General charac- 
teristics of these bodies. 

307. Equivalent and sp. gr. of hydrogen. Origin of the name. Synony- 
mes. Where existing. Discovery. 

308. From what substance is hydrogen usually obtained ? Exp. 1. De- 
composition of water by galvanism. Exp. 2. Decomposition of water by 
heated iron. Exp. 3. Agency of sulphuric acid in promoting the decom- 
position of water. 



HYDROGEN. 



115 



Decomposition of Water by Galvanism. 

Fig. 54. 

Exp. 1. Let the two poles* of 
the voltaic pile, (Fig. 54.) be im- 
mersed in a vessel of pure water ; 
the liquid will be decomposed ; 
oxygen will be given off at the 
positive pole D, and hydrogen at 
the negative pole N. The gases 
may be collected by inverting over 
each pole a glass tube O, and H, 
closed at one end, and filled with 
water. 

As opposite electricities attract 
each other, the oxygen is considered 
as electro-negative, and hydrogen 
electro-positive ; and thus these two 
gases are placed at the head of their 
respective divisions. 

Hydrogen may also be obtained 
by decomposing water with red hot iron. 

Exp. 2. Put a coil of iron wire into a gun barrel, (Fig. 55.) open at both 
ends. The gun barrel is then passed through a furnace. To one end of 
the iron tube or gun-barrel is luted the neck of a retort A, containing 
water; and to the other, a bent tube E, of iron wire. A fire is now lighted 
in the furnace, and the water in the retort is boiled by means of an Argand 
lamp. The steam of the boiling water is decomposed in passing through 

Fig. 55. 





the coil of iron wire in the gun barrel ; the oxygen combines with the iron 
which is found to be converted into the black oxide of iron ; the hydrogen 
passes off into the receiver G. 

Exp. 3. Another mode of obtaining hydrogen by the decomposition of 
water, is very simple. Dilute some sulphuric acid with 8 or 9 times its 
bulk of water, and pour it into a retort, or bottle containing zinc or iron 
filings, f A violent effervescence will immediately ensue, owing to the es- 

* The wire used for the poles should be of platinum, as the oxygen would 
combine with iron wire. 

t The great heat evolved by mixing sulphuric acid and water would en- 
danger the vessel without due care. The acid should be gradually poured 
into the water ; not the water into the acid. 



116 



PROPERTIES. 



cape of hydrogen gas, which is always to be received over water. Here the 
oxygen of the water unites with the metal, forming an oxide ; the latter next 
combines with the acid forming a sulphate of zinc or iron (according as the 
one or the other metal is used) and the hydrogen of the water is liberated. 
The use of the acid consists in its uniting with, and dissolving the oxide 
which forms around the metal, and which would, if not taken up, prevent 
the contact of the metal with the water. 

309. Properties. Hydrogen is combustible, transparent and col- 
orless, a powerful refractor of light, and very strongly electro- 
positive. As commonly obtained, it has a faint, disagreeable 
odor, which, however, does not belong to the gas, but to volatile 
oil mingled with it. It is used for filling balloons, being the 
lightest body known in nature. It is about 14 times lighter than 
atmospheric air, and 16 times lighter than oxygen. Hydrogen 
has never been reduced to the liquid state. It has resisted all 
attempts to resolve it into more simple parts, and is, therefore, 
considered an elementary body. It is scarcely absorbed in 
water, and has neither acid, nor alkaline properties. It is not 
poisonous, but an animal confined in it, dies for want of oxygen ; 
for the same reason, a burning body is extinguished on being 
immersed in this gas. 

Fig. 56. A lighted candle placed under a jar of hydrogen gas, 

(Fig. 56.) is extinguished, though by its flame it will 
set the gas at the mouth of the jar on fire, and may be 
re-lighted, by having the wick brought in contact with 
the flame, when the combustion goes on, because there 
is oxygen to support it. 

Exp. Hydrogen is highly inflammable. Let some iron 
filings, water, and sulphuric acid, be put into a flask, 
(see exp. 3. §308.) and a jet of hydrogen will soon issue 
from a tube fitted to the mouth of the flask ; this jet 
may be set on fire by a lighted taper ; and will burn 
suddenly, with a very faint greenish light. The color 
of the flame, however, appears to depend on impuri- 
ties, as the flame of the purest hydrogen, is scarcely 
perceptible. 

310. If hydrogen be mixed with oxygen in 
proper proportions, and then set on fire, the 
whole burns at once, with a loud explosion. 
The detonation takes place also, but not so violently, if air be 
used, instead of oxygen gas ; the proportions for producing the 
most powerful explosion, are two measures of hydrogen, to one 
of oxygen, or five of air. These explosive mixtures may be 
kindled, not only by flame, and an ignited body, but also by the 
electric spark, and by platinum in that particular form called 




309. Properties of hydrogen. Its elementary nature, &c. Exp. Inflam- 
mable nature of hydrogen. 

310. Explosive and inflammable nature of hydrogen and oxygen. 



FLAME. 



117 



spongy platinum. If a jet of hydrogen gas be directed against a 
piece of spongy platinum, the latter becomes red-hot, and sets 
lire to the stream of gas. 

An apparatus for procuring instantaneous light by means of spongy pla- 
tinum and hydrogen gas will be explained under the head of platinum. 

311. The heat of the flame of hydrogen is very great, even 
when a jet of the gas is burned in the air • but if the gas be pre- 
viously mixed with oxygen, the quantity of caloric evolved, is 
greatly increased ; the heat of the flame thus produced, is con- 
sidered the greatest that can be produced by artificial means. 
For the first application of this fact to useful purposes, science 
is indebted to Dr. Hare, in the 
construction of the oxyhydrogen, 
or compound blow-pipe. 

In this apparatus, the gases 
are confined in separate reser- 
voirs a a, (Fig. 57.) from which 
they are expelled through tubes 
b 6, meeting in a conical piece c, 
in which the gases mix just be- 
fore they are to issue. By this 
plan, all danger is avoided ; for 
the utmost that can happen, is 
the explosion of the mixed por- 
tion of the gases contained in the 
conical jet; a quantity too small 
to do any mischief. The flame 
of the compound blow-pipe, fuses the most refractory substan- 
ces in nature, as platinum, which is quite infusible in the most 
powerful furnaces. This flame is not extinguishable by water. 

312. Flame. The reason why the flame of the mixed gases 
is so much hotter than that of hydrogen, burning in an atmos- 
phere of oxygen, will be obvious, if we reflect, that no combus- 
tible can burn, unless it be in contact with some other substance, 
which acts* as a supporter of combustion. Now, when a column 
of the inflammable gas escapes into an atmosphere containing 
oxygen, only the surface of the column is in contact with the 
supporter, and consequently, only its exterior coat can burn. 
This being consumed, another layer of hydrogen is exposed, and 
burns in its turn ; so that the column is constantly growing small- 
er as it rises, till at last it terminates in a point. Accordingly an 

311. Heat of the flame of hydrogen. Increase of heat from a mixture of 
oxygen and hydrogen. Compound blow-pipe. Dr. Hare's blow-pipe. 

312. Flame. Cause of the great heat of the mixture of hydrogen and oxy- 
gen gases. Difference between ordinary flame and that of the mixture of 
hydrogen and oxygen gases. 




118 COMBINATION OF 

ordinary flame, (as a candle or lamp, or the blaze on the hearth,) 
is conical, and a mere shell of ignited matter ; the interior con- 
sisting of unburnt, inflammable gas. In the compound flame, 
however, each part of hydrogen being already in contact with 
its particle of oxygen, the whole column is in combustion 
throughout its mass. The simple flame, therefore, bears to th 
compound one, the same relation that the surface of the cone 
bears to its volume 

COMPOUNDS OF HYDROGEN AND OXYGEN. 



; 



313. Protoxide of Hydrogen, or water. 1 equiv. hyd. 1 to 1 
equiv. ox. 8=9. Sp. gr. =1. Whenever hydrogen is made to 
combine directly with oxygen, either by explosion or otherwise, 
the compound formed, is water j nor will any variation of the 
proportions in which these gases are mixed, cause the forma- 
tion of any other product j and when either gas is in excess, 
that excess will remain unconsumed after the experiment. Thus, 
if two measures* of each gas, be mixed in a proper detonating 
tube, over mercury, and fired by the electric spark, it will be 
found after the explosion, that three measures have disappeared, 
and that mercury has risen in the tube to supply their place. 
The remaining one measure, consists entirely of oxygen ; so 
that the whole of the two measures of hydrogen, have combined 
with one measure of oxygen. If three measures of hydrogen 
and one of oxygen, be exploded in the same manner, there will 
be a condensation of three measures, and the residual measure 
will be hydrogen. 

Fig. 58. 314. Water fanned by the combination of hy- 

drogen and oxygen gases. Exp. 1st. Hold a 
perfectly clean, and dry, glass vessel over a jet 
of hydrogen gas, the oxygen of the air com- 
bining with the hydrogen, will form an aqueous 
vapor, which will appear on the inner side of 
the glass. Exp. 2nd. Let a current of burn- 
ing hydrogen pass into the mouth of the tube a, 
(Fig. 58.) the glass cylinder b, will soon appear 
covered with dew from the condensation of the 
aqueous vapor, produced by the oxygen of the 
air uniting with the burning hydrogen. 
* By measure or volume, it is found that the atom of hydrogen is twice as 
large as that of oxygen ; thus, as one atom of each unite to form water, and 
the weight of the atom of hydrogen is found, in comparison to oxygen to be, 
as 1 to 8, it follows that the specific gravity of hydrogen is 16 times less 
than that of oxygen. 

313. Equiv. and sp. gr. of water. Combination of hydrogen and oxygen. 
What proportions, in volume, of these gases unite to form water ? 

314. Exp. 1st. 




HYDROGEN AND OXYGEN. 
Fig. 59. 



119 




Exp. 3d. A more complicated apparatus for shewing the formation of 
water by means of the combination of oxygen and hydrogen was invented 
by the French chemist, Lavoisier. " This apparatus consists of a glass 
globe (Fig 59.) with a neck cemented into a brass cap from which three 
tubes proceed, severally communicating with an air pump, and with reser- 
voirs of oxygen and hydrogen. It has, also, an insulated wire, for produc- 
ing the inflammation of a jet of hydrogen, by means of an electric spark. 
In order to put the apparatus into operation, the globe must be exhausted 
of air, and then supplied with oxygen to a certain extent. In the next place, 
hydrogen is to be allowed to enter in a jet, which is to be inflamed by an 
electric spark." — Dr. Hare. 

Exp. 4th. Let a (Fig. 60.) be a glass cylinder, filled with pure oxygen ; 
b, a bell glass containing hydrogen, and partly immersed in a vessel of wa- 
ter, c. On opening the stop cocks, d d, the hydrogen rises through the 
capillary tube /, and on heing inflamed by an electric spark, it burns with 
great force, and drops of water soon collect in the cylinder. 



Exp. 3d. Lavoisier's apparatus. 
Exp. 4th. 



120 



ANALYSIS OF WATER. 



Fig. 60. 



Analysis of Water. 



315. We have shown by synthetic proof , that 
water is composed of two gases. The same fact 
may be demonstrated by a reversed method, that 
of analysis. 

Exp. When water, in the state of steam, is made to 
pass over heated iron, the metal absorbs the oxygen, and 
hydrogen gas escapes. The iron will be found to have 
gained in weight 8 grains of oxygen, for 1 grain of hy- 
drogen obtained. 

Figure 55, shows an apparatus, invented by Dr. Hare, 
by which steam is decomposed by passing over hot iron. 
The gun-barrel to which the retort is cemented, is fitted 
at its opposite end with a flexible leaden tube, for the 
purpose of conducting off" the hydrogen gas. Within the 
gun-barrel (Fig. 61.) is introduced a quantity of iron 
turnings, or refuse card teeth. The glass retort is part- 
ly filled with water. A quantity of charcoal within the 
furnace being ignited, soon heats the gun-barrel to a red, 
and then to a white heat. In the meantime, a chafing 
dish of burning coal is placed under the retort ; the water 
soon boils, is changed to steam, which passes through 
the gun-banel and parts with its oxygen to the metal, 
while the hydrogen escapes through the flexible leaden 
tube, and may be collected. 

It has been shown, (308, Exp. 1st.) that when 

water is subjected to the action of the galvanic 

pile, it will be decomposed, and hydrogen will appear at the 

negative, and oxygen at 
the positive pole. Let a 
glass tube be filled with 
water, corked at both en d s, 
and the two wires of the 
galvanic circle, then put 
throHgh the corks. The 
water being acted upon by 
galvanic electricity, its 
elements separate, hydro- 
gen being attracted to the 
negative pole, and oxygen 
to the positive. 

315. The composition of 
water may be proved by anal- 
ysis. 

Exp. Analysis of water by 
means of an apparatus in- 
vented by Dr. Hare. Analy- 
sis by galvanic action. 




Fis. 61. 





DECOMPOSITION OF WATEK. 121 

Water. 316. The figure represents the com- 
parative bulk of the atoms of hydrogen and 
oxygen as they exist in water ; the form- 
er being twice as large as the latter, as is 
ascertained by the bulk of the two gases 
obtained by the decomposition of water. 
As the weight of the atom of oxygen is 
Chem. Equiv. 9. found to be 8, while that of the atom of 
hydrogen is 1, it follows that the specific 
gravity of oxygen is sixteen times greater than that of hydrogen ; 
so that if its ultimate atom had the same bulk as that of hydro- 
gen, its combining number would be sixteen instead of eight. 

317. Natural history. Water, as obtained from the usual 
sources, is impure. Rain water collected at a distance from 
buildings, is less impure than that from springs, or that which 
has fallen from the eaves of houses, but still contains several 
gases, the odoriferous matter of plants, with traces of animal and 
saline matter. The animal and vegetable matter contained in 
rain water, causes its tendency to putridity. Spring and river 
water, in addition to the same impurities which exist in rain 
water, contain several salts which they acquire from the soil, and 
of which sulphate of lime is one of the most frequent. To these 
salts, water owes the property commonly called hardness ; that 
is, the property of decomposing soap, (or of curdling it, as it is 
usually termed ;) for soap, is in reality, a salt, being composed 
of acid and alkali ; so that when it meets an earthy salt in so- 
lution, a double decomposition ensues ; the soap and the salt ex- 
change acids, and two new salts are formed, one of which floats 
on the surface of the water. A solution of pearlash, shows the 
presence of these salts, by producing a white precipitate. The 
white deposit on the inside of a tea-kettle, in which spring water 
has been much boiled, is a mixture of carbonate and sulphate of 
lime. 

318. The spring water of some localities is harder than that of others, be- 
cause some soils contain more of soluble salts than others. The presence 
of these saline substances, not only communicates a somewhat nauseous 
taste to water, but injures its solvent powers in some particular instances ; 

316. Comparative bulk of the atoms of hydrogen and oxygen. Specific 
gravity of oxygen compared with hydrogen. 

317. Impurities of water. Rainwater. Spring and river water. Cause 
of the hardness of water. Why hard water decomposes soap. Tests of the 
presence of salt in water. Cause of the white deposit on the inside of a 
tea-kettle. 

318. Why the water of some springs is harder than others. Why soft 
water is better for making tea than hard water. Effect of boiling or freez- 
ing water in relation to its impurities. Distillation of water. 

11 



122 HYDROGEN. 

thus, it has been found that of equal portions of rain and spring water, the 
former will extract from a given portion of tea, a considerable greater 
quantity of its soluble matter than the latter. The gaseous and other vola- 
tile bodies contained in water, may be expelled by boiling it ; they also par- 
tially escape, when water freezes, so that water in sufficient purity, for 
many purposes, may be obtained by melting fresh fallen snow. Such water 
is flat, tasteless and insipid; the liveliness of water, in its ordinary state, 
being due to the gases it holds in solution. But the only way of obtaining 
perfectly pure water, is by distillation in silver vessels, in which process, 
the saline impurities remain in the distilling vessel, while the water is con- 
verted into vapor and passes into the condenser.* 

319. Physical Properties. Pure water is transparent, color- 
less, tasteless and inodorous : a non-conductor of caloric, an im- 
perfect conductor of electricity, and a powerful refractor of light. 
It is the unit of specific gravity for solids and liquids, and is 828 
times heavier than air. At 212° F., the barometer standing at 
30 inches, the water boils ; it freezes at 32°, and in congealing, 
shoots into needle shaped crystals, which cross each other at 
angles of 60 and 120°. 

320. If the aeriform bodies that previously existed in water, be expelled 
by boiling, it absorbs every gas, but in very different proportions ; some 
gases being dissolved in very minute quantities, while of others, water will 
take up several hundred times its own bulk. The quantity absorbed may 
be increased by pressure, and is in direct proportion to it; on removal of 
the additional pressure the excess of gas escapes with effervesence, as in the 
instance of common soda water. The gas contained in water under ordin- 
ary atmospheric pressure, is expelled by heat, or by removing the pressure 
with an air pump. Water has a very extensive range of affinities, and is, 
therefore, an important chemical agent ; it is the most general solvent we 
possess. 

321. Water enters into two kinds of combination besides solutions, and 
in these it unites in definite proportions; these combinations exist 1st, in 
crystals ; 2nd, in hydrates. 

1st. Many bodies in crystalizing from their solutions in water, carry with 
them a portion of water which constitutes an essential part of the crystal, 
and which cannot be separated without destroying its form and transparency. 
Water thus combined, is called water of crystalization. It is believed to be 
in a state of greater solidity in this combination than in the form of ice. It 
may be expelled by heat ; and the crystal will then fall into powder. 

2nd. Water exists in another class of compounds called hydrates. Some 
of these are liquids; for example, the strongest sulphuric acid of commerce 

* A coifee apparatus invented in France, makes the vapor of water pass 
through the ground coffee. The aromatic portion is thus extracted, with 
less of the bitter principle, than in the usual method. The water being dis- 
tilled before it comes in contact with the coffee, all the impurities of the for- 
mer are left in the boiler. 



319. Physical properties of water. 

320. Absorption of gases by water. Effect of pressure on absorption. 
Solvent power of water. 

321. Compounds where water exists in definite proportions. Water of 
crystalization. Liquid, and solid hydrates. 



HYDRACIDS. 123 

contains an atom of water to an atom of acid, and is therefore a hydrate of 
sulphuric acid ; the strongest nitric acid, that can be produced consists of 
one equivalent of acid and two of water. Many hydrates, however, are 
solid ; and the water they contain is in the greatest state of condensation in 
which it is known. Much caloric is consequently evolved during the for- 
mation of hydrates ; thus, in the slakiog of lime, which operation is in fact 
the conversion of pure lime into a hydrate, the heat evolved, amounts to 
800° F. Some hydrates are decomposed by heat ; but others retain the com- 
bined water at the highest temperatures. 

322. Deutoxide of Hydrogen. 2 ox. 16, to 1 hyd. 1 = 17, its 
equivalent. This is called deutoxide, (or binoxide) because 2 
atoms of oxygen combine with one of hydrogen ; and sometimes 
the peroxide, it being the highest combination known of oxygen 
with hydrogen. It was discovered by Thenard in 1818. 

This substance, cannot be formed by the direct union of the two gases. 
The only method at present known, is the oxidation of water by means of 
the peroxide of barium. In this process is added to water a portion of hydro- 
chloric acid, and the peroxide of barium; the latter, parting with oxygen, is 
reduced to a protoxide which unites with the hydrochloric acid, while the 
liberated oxygen unites with the water, converting it into deutoxide of hydro- 
gen. Sulphuric acid is added to precipitate the protoxide of barium. 

323. The deutoxide of hydrogen is transparent and colorless, 
heavier than water, its sp. gr. being 1.452; it is volatile, inodo- 
rous, and has a metallic taste. It thickens the saliva, whitens the 
skin, and is, to a degree, caustic. It bleaches powerfully ; its 
oxygen being considered the active bleaching principle. It is 
very easily decomposed, either by the contact of other bodies or 
by heat ; and can only be preserved by keeping it at a temper- 
ature of about 32° F. If heat be applied to it in its concentra- 
ted state, half of its- oxygen suddenly escapes with a violent ex- 
plosion, and the residual product is water. The deutoxide of 
hydrogen has not been applied to any of the arts, and at present 
is only interesting to the Chemist, as a peculiar and striking il- 
lustration of the doctrine of definite proportions.* 



CHAPTER XIII. 

HYDRACIDS. 

324. A class of substances possessing acid properties are term- 
ed hydr acids, (or hydro acids,) because they contain hydrogen as 

* See Thenard's Traitie de chimie, and other elaborate works on this sub- 
ject. 

322. Proportions of the deutoxide of hydrogen. Name. Discovery. 
Manner in which it may be formed. 

323. Properties. Decomposition. Effects of heat upon it. Its action 
with metals and oxides. Its application to useful purposes. 



124 HYDRACIDS. 

one of their elements. Acids are the most remarkable products 
obtained by the union of both oxygen and hydrogen with other 
bodies. And yet, these two gases, so powerful in their combi- 
nations with other bodies, and standing each at the head of two 
distinct electro-chemical classes, form by their natural combina- 
tion with each other, the mild, inoffensive compound, water, 
with no trace of acid properties whatever. 

Some of the oxacids or oxyacids, we have already noticed, as 
Chloric, Iodic, Bromic and Fluoric acids ; and as we proceed to 
consider the electro-positive bodies, we shall have occasion to 
describe other important acids formed by a combination of those 
bodies with oxygen. 

All acids are formed by the union of a substance called the 
base or radical, with an acidifying principle. In chloric acid, 
chlorine is the radical and oxygen the acidifier. 

325. Of the radicals of the hydracids, some are simple bodies, and others 
compound. All the simple radicals are electro-negative, except sulphur ; 
and even that is so while in combination with other electro-positive bodies. 
The compound radicals are electro-positive in relation to oxygen and other 
substances of the same class, but go to the positive pole, (and therefore, are 
electro-negative,) when just separated from combination with hydrogen or 
a metal. So that as regards the part, they act in composition of a hydracid, 
they may all, (both simple and compound,) be considered as electro-negative. 
They all have feeble atflnities for compound bodies, but powerful ones for 
the simple electro-positive substances, and when their compounds with the 
latter are put into water, (provided they be soluble,) that fluid is decompos- 
ed, its oxygen unites to the electro-positive elements to form an oxide, and 
its hydrogen unites to the electro-negative radical to form a hydracid. If 
the oxide thus formed be a salifiable base, it combines with the hydracid to 
form a salt; if the compound put into water be insoluble, no action takes 
place. Thus common salt is chloride of sodium ; dissolved in water it is 
muriate of soda, hydrochloric acid being formed by the chlorine and the hy- 
drogen of the water, and soda by the sodium and the oxygen of the water ; 
but chloride of silver is quite insoluble in water, and undergoes no change 
in it. When a salt of a hydracid has been thus formed, the binary com- 
pound of the radical and the metal may be again obtained, by evaporating 
the solution to dryness, and heating the dry mass to expel the water which 
is re-formed. 

326. The compounds of metals with the radicals of hydracids are called 
Haloid bodies, from their resembling salts in their characters and habitudes ; 
the name haloid being derived from the Greek hale, sea-salt and oidos, like. 

324. Why are the hydracids so named ? Products of the union of oxygen 
and hydrogen with other bodies, and with each other. The radical and 
acidifying principle of acids. 

325. Radicals of the hydracids. Electrical nature of the simple and com- 
pound radicals. Effect of water in decomposing compounds formed between 
electro-positive and electro-negative bodies. Change which takes place in 
the chloride of sodium when dissolved in water. How may the chloride of 
sodium, or binary compound of the radical and metal, be again obtained ? 

326. Haloid bodies. Five most important radicals of the hydracids. Or- 
der of their affinities for hydrogen. Their affinities for oxygen. 



HYDRACIDS. 125 

Indeed, as had just been stated, they appear to become salts on being dis- 
solved. 

The five most important of the simple radicals of the hydracids are, 

1. Chlorine, 3. Iodine, 

2. Bromine, 4. Fluorine, 

5. Sulphur. 

Fluorine having never been obtained in a separate state, the comparative 
energy of its affinity for hydrogen is not ascertained. Neither is it known 
whether it can combine with oxygen or not. The other four radicals, are 
placed in the above list according to the order of their affinities for hydro- 
gen ; so that chlorine will decompose hydrobromic, hydriodic and hydrosul- 
phuric acids, forming hydrochloric acid and liberating the other radicals; 
Bromine acts in the same way with hydriodics and hydrosulphuric acids ; 
and iodine with hydrosulphuric acid only. The affinities of *hese bodies for 
oxygen, are in the inverse order of their attraction for hydrogen : sulphur 
having the greatest, and chlorine the least affinity for oxygen. 

327. The hydracids may be obtained, by pouring strong sulphuric acid on 
certain compounds, of their respective radicals with a metal. The water, 
which even the strongest liquid sulphuric acid contains, furnishes hydrogen 
to the radical and oxygen to the metal ; the metallic oxide thus formed, 
unites to the sulphuric acid and forms a sulphate, and the hydracid is left 
free. The hydracids are all, in reality gases ; those of chlorine, bromine 
and iodine contain equal volumes of the two constituents, united without 
any condensation, so that one volume of the radical and one of hydrogen 
constitute two volumes of the hydracid. The specific gravity of these three 
hydracids is therefore half the sum of the specific gravities of their constit- 
uents. The gaseous hydracids are generally heavier than air, and have 
strong attraction for water. Some of them are absorbed by that liquid to 
the amount of several hundred times its bulk. During the formation of 
these watery solutions, condensation takes place, heat being evolved, and 
the liquid resulting is heavier than water. It is in this state of solution that 
the hydracids are used in chemical operations ; heat will expel from the 
liquid the greater part of the gaseous acid. 

328. The hydracid gases are decomposed when electrified with the proper 
quantity of oxygen gas, water being formed and the radical set at liberty ; 
some of the metals also, decompose them with the aid of heat, uniting with 
the radical and liberating the hydrogen. 

The liquid hydracids, that is the solution of the gaseous acids, act differ- 
ently on different metallic oxides; with some protoxides, the acid combines to 
form salts ; with others, a mutual decomposition occurs, and water is pro- 
duced, together with a binary compound of the radical and the metal; but, 
in such cases, the latter compound is insoluble. Some of the peroxides 
yield a portion of their oxygen to the hydrogen of the acid, forming water 
and eliminating the radical ; and thus are reduced to the state of protoxides, 
which combine with the radical acid and form salts. The first process 
given for obtaining chlorine, (§ 262,) is an example of this decomposition. 
With some oxides the hydracids do not re-act in any manner. 



327. Manner in which the hydracids may be obtained. Nature and con- 
stitution of the hydracids. Attraction of the gaseous hydracids for water. 

328. Their decomposition. What are liquid hydracids 3 and how do thev 
affect metallic oxides ? 

11* 



126 



HYDROCHLORIC ACID. 



Fig. 62. 



329. Hydrochloric or muriatic acid. 1 chl. 36, to 1 hyd. 
1-37. Sp. gr. 18. 21 hyd.=l, 1.2694 air=l. 

This was at first known under the names of marine acid, and 
spirit of salt, and was regarded as an oxacid, formed by the 
union of oxygen with an imaginary base, named muriatium ; af- 
terwards it was called muriatic acid (from muria, sea-salt) which 
name it retained until the importance of shewing the constitu- 
ents of bodies by their chemical names had become fully estab- 
lished. 

It is obtained by pouring 
strong sulphuric acid on 
chloride of sodium, (com- 
mon salt,) contained in a 
tubulated glass retort A, 
(Fig. 62) and applying heat 
at C. The tube of the re- 
tort, B passes under a re- 
ceiver filled with mercury 
and inverted over a mercu- 
rial trough. The water of 
thesulphuric acid furnishes 
oxygen to the sodium, and 
hydrogen to the chlorine ; 
the newly formed oxide of 
sodium, unites with the sul- 
^^^Ss phuric acid forming sulphate 
" of soda, and the hydrochloric 

acid being disengaged, pas- 
ses through the tube of the retort into the receiver. The dense white fumes 
which appear over the mercurial trough, are caused by the escape of some 
portion of the hydrochloric acid gas, which unites with the aqueous vapor 
of the atmosphere, 

330. Physical Properties. Hydrochloric acid is colorless, 
transparent, and of a peculiar odor. It is irrespirable when 
pure ; but if diluted with air, may pass into the lungs, but, even 
in that case, it exerts a corrosive action on them. Its affinity 
for water is great, a volume of that fluid absorbing 480 volumes 
of the gas, and forming the liquid muriatic acid. 

331. The process of forming hydrochloric acid, is very conveniently per- 
formed, by an apparatus called, from its inventor, Woulfe's apparatus. 
(Fig. 63.) The retort a, contains common salt and sulphuric acid ; a gentle 
heat being applied, the muriatic gas is disengaged and passes into the globe 
or first bottle, b, which, with the other bottles, contains water. The first 
bottle serves to condense any vapor which may be mingled with the muria- 
tic acid gas, and the liquid in this will then be an impure solution of muria- 

329. Equiv. and sp. gr. of hydrochloric acid. Synonymes. Mode of ob- 
taining hydrochloric acid. Rationale of the process. 

330. Properties. 

331. Mode pf obtaining hydro-chloric acid by means of Woulfe's appara- 
tus, Why should the bottles be kept cool ? Further proof of the affinity 
of this gas for water. 




CHEMICAL PROPERTIES. 127 

tic acid. From the globe b, the purified gas proceeds through the bent tube 
to the next bottle, where a portion is absorbed by the water ; the excess of 
gas then passes on, and a portion is, in like manner, absorbed by the liquid. 
Should some portion of the gas escape absorption, it may by the last tube 
be conducted under a receiver in the pneumatic cistern. The number of 
bottles may be increased or diminished. The straight tubes c, c, c, are call- 
ed safety tubes. While they oppose atmospheric pressure to the escape of 
the gas, they prevent the vacuum which would ensue from a sudden absorp- 
tion of the gas, and which might draw in the impure acid contained in the 
globe. 




During this absorption a great condensation takes place, and heat is con- 
sequently evolved ; so that the bottles used to contain the liquid must be 
kept cool by ice, in order that the solution may be saturated. As a further 
proof of the affinity of this gas for water, if a piece of ice be put into a 
jar of the gas, it will be melted almost as rapidly as by a hot iron; and the 
gas is absorbed by the water thus formed. 

332. Chemical properties. This gas possesses acid properties 
in a very high degree ; combining with salifiable bases, redden- 
ing litmus paper, &c. j many of the metallic oxides react on it 
by the aid of heat, water and chloride of the metal being formed ; 
several of the metals also decompose it by means of their affinity 
for chlorine ; in such cases, a chloride of the metal is formed and 
hydrogen gas set free. It is the only known compound of chlo- 
rine with hydrogen, and composed of equal bulks of chlorine and 
hydrogen gases, united without any condensation. 

333. Nitro- hydro chloric or JVitro-mujiatic acid consists of 1 
part of nitric acid with 4 of hydrochloric. It was called by the 
alchemists aqua regia, on account of its remarkable property of 
dissolving gold and platinum. Soon after the acids are mixed, 
the liquid grows deeper colored, and, at last, becomes winecol- 
ored, and chlorine is evolved. On heating the mixture, chlorine 
and deutoxide of nitrogen are expelled, after which it no longer 
dissolves gold ; hence it appears that chlorine is the cause of its 
solvent property with regard to that metal. 

334. Hydrobromic jicid is composed of equal volumes of vapor of bromine 

332. Chemical properties. 

333. Nitro-hydrochloric acid. 

334. Composition of hydrobromic acid gas in respect to weight and vol- 
ume. Resemblance to muriatic acid. How obtained ? 



128 NITROGEN. 

and of hydrogen. In odor, and in other properties it resembles hydrochloric 
acid. Thus it forms salts with some oxides, and is decomposed by others ; 
it has a powerful affinity for water. It is obtained by exposing bromine to 
the action of sulphuretted hydrogen gas, when the former takes the hydro- 
gen, and sulphur is deposited ; or, by mixing bromine, phosphorus and water 
in a small retort and applying heat ; in which case, the phosphorus and bro- 
mine join in decomposing water, the former taking the oxygen and the lat- 
ter the hydrogen. It was discovered by M. Balard. 

335. Hydriodic Acid contains one volume in bulk of iodine vapor, and one 
of hydrogen gas, combined without alteration of bulk. It is consequently, 
constituted like hydrochloric and hydrobromic acid gases, which it also re- 
sembles in its general properties ; being decomposed by the same agents 
and under the same circumstances. The analogy extends even to its odor 
and its solubility in water. As the affinity of iodine for hydrogen is less 
than that of either bromine or chlorine, those substances will each decom- 
pose hydriodic acid, forming the corresponding hydracid, and eliminating 
iodine. Hydriodic acid gas, may be made by bringing iodine into contact 
with sulphuretted hydrogen gas, when sulphur will be set free, and iodine 
will take its place ; but this process is not commonly to be preferred. The 
best way of procuring this gas, is to moisten a mixture of iodine and phos- 
phorus, in a very small retort, and apply heat, collecting the gas over mer- 
cury. As in the formation of hydrobromic acid gas, the oxygen of the 
water is taken by the phosphorus ; so in this case, the hydrogen combines 
with iodine. The solution of hydriodic acid gas in water, or liquid hydriodic 
acid, is best obtained by passing hydrosulphuric acid gas into water in 
which iodine is held suspended ; the oxygen of the water disengages the 
sulphur, and the hydrogen combines with iodine. 

336. We have treated of hydrofluoric add, under the head of its radical, 
fluorine. Hydrosulphuric acid y will be considered under the head of sul- 
phuretted hydrogen, the name by which it is usually distinguished. Hydro- 
cyanic acid, is a hydracid of a very peculiar nature, but cannot be well un- 
derstood, until after the composition of its radical cyanogen shall have been 
explained. 



CHAPTER XIV. 

NITROGEN. 



oorr v • ^ by vol. 100 } c ( 0,9722 Air=\ 

337. E 9 mv. \ d wdght u j Sp. gr. j ^ Hyd=l 

Nitrogen is a permanent gas, and constitutes nearly four 
fifths of the atmosphere in bulk, If a lighted taper be covered 

335. Composition of hydriodic acid gas. Its analogies with hydrochloric 
and hydrobromic acids. May be decomposed by them. Mode of obtaining 
it. Liquid hydriodic acid. 

336. What other hydracids are there besides the hydrochloric, hydrobro- 
mic, and hydriodic ? 

337. State in which nitrogen exists. Gas which remains when the oxy- 



NITROGEN. 



129 



with a large tumbler, or bell glass, the combustion will soon 
consume the oxygen of the air, and nitrogen will remain. For 
experiments, nitrogen may be better obtained by burning phos- 
phorus under a bell glass inverted over water. The phosphorus, 
combining with the oxygen of the air, forms phosphoric acid, 
which appears at first in dense white fumes, but soon settles upon 
the surface of the bell glass, and may be rinsed offin the water. 
The oxygen being now absorbed from the air, the bulk of the 
residue will be found, when cooled, to be condensed,* and on 
testing its properties it will be found to be nitrogen. 

Dr. Hare has invented the Fig. 64. 

apparatus here represented 
(Fig. 64.) for obtaining nitro- 
gen in large quantities. Phos- 
phorus is placed in a cup sus- 
pended in a glass vessel. Wa- 
ter is introduced bv means of 
the tunnel T. The bladder, B, 
gives room for the expansion of 
the air which takes place when 
the phosphorus is burning. 
The nitrogen gas having been 
obtained by means of consum- 
ing the oxygen, it is expelled by 
pouring more water into the 
funnel, which taking its place 
in the lower part of the vessel 
expels the gas through the tube 
P, the stop cock being turned so 
as to admit it to pass. The gas 
is thus received into vessels for 
the purpose of experiment. 
Slight impurities consisting of 
carbonic acid, and vapor of 
phosphorus, may be removed by 
solution of caustic, potassa, or 
lime. Several other substances, 
having affinities for oxygen will 
absorb it slowly from air, 
among these, are,protosulphate 
of iron, and the alkaline hydrosulphurets. Carbon and sulphur, do not con- 
sume the oxygen of the air so completely as phosphorus does, and the pro- 
ducts of their combination are sulphurous and carbonic acids, which being 
both gaseous, would, therefore, remain mixed with the nitrogen, and require 

* The fact of this diminution of bulk is known by the water over which 
the bell glass is inverted rising higher in the glass than before the burning 
of the phosphorus. 




gen in an inclosed portion of atmospheric air is burned. Obtained for ex- 
periments. Objections to the use of carbon and sulphur. Obtained from 
animal matter. Explain fig. 64. 



130 ATMOSPHERIC AIR. 

a separate process for removing them. Nitrogen is a constituent of animal 
matter, and may be obtained by its digestion in diluted nitric acid. 

338. Physical and Chemical properties. Nitrogen is colorless, 
transparent, tasteless, inodorous, permanently elastic, and lighter 
than common air. It does not support the combustion of burn- 
ing bodies, neither will an animal live in it ; but in neither of 
these cases, is it supposed to exert any positive action ; the ef- 
fects being due merely to the absence of oxygen ; as the innox- 
ious substance, water, will extinguish flame or destroy animal 
life by excluding the air, and consequently the oxygen which is 
necessary to support combustion and respiration. Indeed, ni- 
trogen seems to possess no active properties, and can only be 
described by negatives. It tends to combine mostly with the 
electro-negative bodies ; but even these affinities are not very 
energetic. As might be expected from its weak affinities, its 
combinations are generally decomposed with great facility ; the 
chloride and iodide of nitrogen, are decomposed with loud explo- 
sion by friction, slight increase of temperature, or the contact 
of other bodies. Water absorbs only a minute portion of ni- 
trogen gas. It has a peculiar affinity for caloric, and is an in- 
gredient in most of the fulminating compounds. 

339. Nitrogen was discovered about the year 1770, by Dr. 
Rutherford of Edinburgh, and Scheele of Sweden. It was at 
first called mephitic gas, or non-respirable air, and afterwards by 
the French Chemists, named azote, or life destroyer, (from the 
Greek, a, to deprive of, and zoe, life.) The latter name implies 
active properties, such as this gas does not possess. For the 
name, azote, has been generally substituted that of nitrogen, 
(from the Greek word gennao to produce, combined xvhhnitro,) 
signifying to produce nitro, or nitric acid. It constitutes f of 
the atmosphere, exists in all animals and some plants, and in 
springs in Scotland and the state of New- York. 

Atmospheric Air. 

340. The atmosphere is a mass of gaseous matter, surround- 
ing the earth and accompanying it in its revolutions. It pos- 
sesses weight, upon which property depends the action of the 
sucking pump, the barometer, and the support of water or mercu- 
ry in an inverted bell glass, above the level of the exterior liquid. 

On v/eighing a glass flask full of dry air, exhausting it carefully, and 

338. Its physical properties. Is not a supporter of combustion. Its af- 
finities not energetic. Why its compounds are easily decomposed. 

339. Discovery and name. 

340. Nature of the atmosphere. Its weight. 



ATMOSPHERIC AIR. 131 

weighing again, it will be found to lose weight by the exhaustion in the 
proportion of 30£ grains for every 100 cubic inches of air withdrawn; — 
this being when the barometer stands at 30 inches, and the thermometer at 
60° Fahrenheit. Air is, therefore, 831 times as light as water, and about 
1 1260 times as light as mercury. It is taken as the unit of specific gravity 
for aeriform bodies. 

341. From the observations of Dr. Wollaston and others, it seems to be 
established that the atmosphere is limited ; and its extent is estimated at 
about 45 miles. As the air is more and more rare, as the distance from 
the earth increases, and as its expansive force decreases in the same ratio 
as its density, it follows, that there must be a point at which its elastic force 
is just counteracted by the earth's attraction. If the atmosphere were to 
expand without limit into space, the sun and the other planets would attract 
a portion of it to themselves, and would have atmospheres of the same kind 
as ours ; a circumstance which is quite inconsistent with astronomical ob- 
servation. Dr. Wollaston, from a series of observations, considers that 
this extreme rarefaction might take place, but for the fact that the atmos- 
phere consists of indivisible ultimate atoms, that can be no farther rarefied. 
34-2. The atmosphere is highly elastic and compressible. 
When the pressure upon a confined portion of it is doubled, it 
will be reduced to half its original bulk ; or, if half the original 
pressure be removed, it will expand to double its former bulk ; 
in other words, its density is directly as the pressure, and its bulk 
in the inverse ratio to that pressure. This law is good also, for 
all aeriform bodies, so long as they continue in the aeriform state. 

343. The temperature of the air is lower as we ascend, for as it must ab- 
sorb caloric in order to expand, and this can be derived from no external 
source, it must render latent its own sensible heat ; for radiant caloric 
passes through gaseous and aeriform media, without affecting them ; so that 
the higher strata of air, though nearer the sun, derive no heat from it. The 
decrease of temperature is estimated at about one degree for every 300 feet ; 
so that there is, in every latitude, some point in the atmosphere at which 
ice never melts. This point at the equator, is about 15207 feet from the 
earth's surface; and the distance decreases gradually toward the poles, 
where it is at the earth's surface. 

344. The atmosphere is essentially composed of nitrogen and 
oxygen gases. Many other bodies are found in it, such as car- 
bonic acid, watery vapor, the odoriferous matters of plants, &c. 
&c. ; of these, the first two are the most constant, and in the 
greatest quantity ; but even they vary in their proportions, which 
are never so large, compared to the whole mass, as to allow us 
to consider these bodies otherwise, than as accidental impuri- 
ties. The carbonic acid is never more than 6.2 parts in 10.000 
of air. 

341. Limited extent of the atmosphere. Dr. Wollaston's argument 
drawn from the limited extent of the atmosphere respecting ultimate atoms. 

342. Elasticity and compressibility of the atmosphere. Temperature. 

343. Gradual decrease of temperature. 

344. Composition of the atmosphere. 



132 



ATMOSPHERIC AIR. 



Eudiometry. 



345. After the discovery of oxygen, it was for some time believed, that 
the proportion in which it was contained in the atmosphere, varied at differ- 
ent times and places; and that the salubrity of a place, depended on the 
quantity of oxygen in the air around it. Hence the analysis of air was call- 
ed "Eudiometry/' or the "measurement of quantity," and this name has 
been retained, though the supposition from which it arose, has been shown 
to be false. 

Many eudiometers have been invented. They consist, in general, of tubes 
adapted to an apparatus for absorbing, or consuming the oxygen of a given 
quantity of air, and for measuring the residuum. The purity of the air is 
estimated by the quantity of oxygen which it is found to contain. Various 
substances which will absorb, or disengage the oxygen from a confined por- 
tion of air, and neither mix with, nor affect the volume of nitrogen, have 
been used in eudiometry. Bui the only analysis of air susceptible of perfect 
accuracy, is founded on the constancy of the proportion in which oxygen and 
hydrogen unite when burned together. 

346. If we put into a strong tube inverted over mercury, 5 measures of 
dry air, and add to this, 2 measures of pure and dry hydrogen gas, and then 
explode the mixture by the electric spark, or otherwise, we shall find after 
the tube has cooled, that just three measures have disappeared, and that 
the mercury has risen to fill their places. Now of these three measures, 
two we know to be hydrogen ; and we also know that two measures of hy- 
drogen, by explosion, condense one measure of oxygen. If we add more hy- 
drogen to the residual four measures of gas, we can no longer produce an 

Fig. 65. explosion; whereas, if we had not originally added enough hy- 
drogen, there would still have remained an excess of oxygen 
after the experiment. 

» 347. Five measures of air, then, contain exactly one measure 
-0 of oxygen ; and the remaining four measures, on examination, 
will prove to be nitrogen. This is the composition of atmos- 
pheric air; and the same unvarying result has been obtained 
at whatever season, height, or latitude the air may have been 
collected for experiment. So that it may be considered esta- 
blished that the atmosphere throughout, its whole mass, con- 
sists of nitrogen and oxysen gases in the proportion of 80 per 
cent, of the former, and 20 per cent, of the latter. The appara- 
tus for performing the analysis, has been made in various forms. 
Itisalways, essentially, however, a strong glass tube a, (Fiij. 
65.) open at one end ; and perforated near the closed end, by 
two metallic wires b b, of which the points are opposite and 
within one tenth of an inch of each other. These wires serve 
for passing an electric spark into the mixture of gases. 




345. Origin of the term eudiometry. Construction and use of eudiome- 
ters. 

346. Manner in which the constitution of the air may be demonstrated. 
Proportions of oxygen and nitrogen contained in it. These proportions do 
not vary. 

347. Apparatus for analyzing the air. 



ATMOSPHERIC AIR. 133 

348. The atmosphere is generally regarded as a mechanical mixture of the 
two component gases. Some, however, prefer the supposition, that it is 
a chemical compound. The reasons for the latter opinion are, briefly, 

1st. That the proportions of nitrogen and oxygen are everywhere the 
same ; whereas, if air were a mere mixture, the heavier gas would be found 
most abundantly, in the lower strata. 2nd. The proportions are definite, 
and accord with the numbers established as the atomic weights of oxygen 
and nitrogen ; agreeably to which, the atmosphere consists of two atoms of 
the latter to one of the former. 

But the investigations of Mr. Dalton, and especially of Dr. I. K. Mitchell 
of Philadelphia, have proved, that gases have a strong tendency to diffuse 
themselves through each other, contrary to gravity, and in spite even of the 
interposition of a bladder or thin sheet of india rubber ; and this, too, when 
no chemical affinity can be supposed to exist between them. If we fill a 
phial with hydrogen gas, and another with carbonic acid gas, connect them 
only by a capillary tube, and place them so that each gas shall be in its 
natural position, viz., the light hydrogen above, and the heavy carbonic acid 
below ; it will be found after some time, that the carbonic acid has ascended, 
and the hydrogen descended, contrary to gravity in each case ; and that the 
gases are equally mixed in both phials. In this case, no chemical affinity 
has been supposed to exist between the gases operated on. Furthermore, 
the facility with which bodies possessing affinities for oxygen, attract it from 
the atmosphere, is too great to admit the belief that it is chemically combin- 
ed there. Again, the specific gravity and refracting power of the air, are 
arithmetical means between those of nitrogen and oxygen ; whereas, in 
cases of chemical combination, these two properties seldom escape altera- 
tion. And lastly, by merely mixing the two gases in the proper proportions, 
we can imitate the atmospheric air perfectly ; whereas, it is only with great 
difficulty that we can make them combine, so as to produce one of the un- 
doubted compounds of nitrogen and oxygen. It seems, therefore, highly 
probable that the atmosphere is a mere mixture of its components. 

349. The oxygen of the air is the active constituent; to it are owing the 
agencies of air in supporting combustions and respirations, and in most of 
the chemical changes in which it is concerned. The use of the nitrogen is 
not fully ascertained. It is generally held to be a mere diluent, by means 
of which, the oxygen is prevented from stimulating the system too highly. 
There is ; however, little doubt that some nitrogen is absorbed in the process 
of respiration. It might be supposed that the immense consumption of oxy- 
gen in combustions, respiration, spontaneous decompositions, and other 
operations, which are incessantly going on, would ultimately alter the pro- 
portions of the constituents of the atmosphere, to an extent that would ren- 
der it unfit to perform its office. Doubtless this would be the case without 
some compensating circumstance. Only one such circumstance is known, 
and that is vegetation. It is ascertained that plants in the day-time, absorb 
carbonic acid, of which they appropriate the carbon, and restore the oxygen 
to the atmosphere. In the night, the contrary process goes on; the vegeta- 
bles absord oxygen and evolve carbonic acid. But it appears that the quan- 

348. Objections to the theory that air is a chemical compound of the gases 
and not a mere mechanical mixture. Answer to these objections and argu- 
ments in favor of the theory. 

349. Agencies of oxygen and nitrogen in the atmosphere. In what man- 
ner is it known, that air is replenished with oxygen, to make up that which 
it loses by combustion, respiration, &c. Do the other compounds of nitro- 
gen and oxysen resemble atmospheric air ? 

12 



134? NITROGEN AND OXYGEN. 

tity of oxygen absorbed in the night, is less than that given out during the 
day ; so that vegetation tends to preserve to the atmosphere its due portion 
of oxygen. Whether this cause is alone sufficient, or whether oxygen is 
furnished by other sources is a question yet to be decided. 

On account of the doubt which exists, whether air is a mechanical mix- 
ture or chemical compound of nitrogen and oxygen, we have treated of it 
under a separate head. All the certain chemical combinations of these two 
gases, are widely different in their properties, from this mild and inoffensive 
agent. 

Chemical Compounds of Nitrogen and Oxygen. 

350. There are five compounds of nitrogen and oxygen, all of 
which conform strictly to the law of multiple proportions. The 
three highest in oxidation are acids ; at the ordinary tempera- 
ture, their natural form is that of liquids, exceedingly volatile, 
and uniting in all proportions with water. The remaining two 
are gases, neither acid nor alkaline, and with little affinity for 
water. 

Definite compounds of oxygen and nitrogen. 



Protoxide of nitrogen, 


Nitrogen 14 


added to oxygen 8 


Deutoxide of nitrogen, 


H 14 


" " 16 


Hypo-nitrous acid, 


" 14 


(( it 24 


Nitrous acid, 


" 14 


« " 32 


Nitric acid, 


" 14 


" " 40 



351. Protoxide of Nitrogen is the well known exhilarating gas, 
often called nitrous oxide. It is prepared, by heating nitrate of 
ammonia in a small glass retort, and may be collected over wa- 
ter, which should be warm, in order to prevent, as much as pos- 
sible, the absorption of the gas. Care must be taken that the 
temperature does not rise above 500° F. ; the melted salt should 
be kept in a state of uniform and moderate effervescence, till the 
whole disappears or enough gas has been collected. 

The rationale is as follows. Nitric acid and ammonia constitute the salt 
called nitrate of ammonia. Nitric acid consists of 'nitrogen, 1 equivalent, and 
oxygen, 5 equivalents. Ammonia contains nitrogen, 1 equivalent, and hydro- 
gen, 3 equivalents. The 3 equivalents of hydrogen with 3 of oxygen form 3 
of water ; and the remaining 2 equivalents of oxygen with the 2 of nitrogen, 
constitute 2 equivalents of nitrous oxide. 

352. Physical and chemical properties. Nitrons oxide gas is 
colorless, has an agreeable but faint odor, and a sweetish taste, 
and dissolves in about its bulk of water at 60°. Its specific 

3c0. How many chemical compounds of nitrogen and oxygen are there ? 
Names and constitution of these compounds. 

351. How is the protoxide of nitrogen prepared ? Rationale. 

352. Properties. Why do bodies burn in this with more brilliancy than 
in common air ? 



RESPIRATION. 135 

gTavity is about 1.5. In mixture with an equal bulk of hydro- 
gen, it explodes violently, on the application of flame, or the 
electric spark. As a given bulk of this gas contains 2^ times 
as much oxygen as an equal bulk of air, bodies burn in it with 
proportionate brilliancy. Thus, a recently extinguished candle, 
of which the wick is still red hot is relighted, on being plunged 
into it, and burns with great splendor. Sulphur and phosphorus, 
previously ignited, burn very rapidly and brightly, when 
immersed in this gas. The combustibles, in these cases, unite 
with the oxygen of the gas, and set the nitrogen free. 

353. Respiration. Exhilarating gas was shown by Davy to 
support respiration for three or four minutes, but no longer. It 
produces strong excitement, usually of an agreeable kind, with 
a rapid flow of ideas, and an irresistible propensity to some kind 
of muscular action. It has been supposed that by this test the 
real character of an individual was developed ; but the grave 
sometimes become suddenly gay, the coward bold, the meek 
quarrelsome ; and it might as justly be said, that insanity ex- 
hibits the real disposition. Some instances have occurred in 
which instant and alarming insensibility, and mental derange- 
ment have resulted from its respiration.* 

354. Deutoxide of nitrogen, called also binoxide, nitrous gas, 
and nitric oxide. Most of the metals, and many other oxidable 
bodies take a portion of the oxygen from nitric acid when brought 
into contact with it. In all such instances, the nitric acid is re- 
duced to some of the lower compounds of nitrogen and oxygen ; 
and, in a few cases it is entirely deprived of oxygen, so that 
pure nitrogen only remains. The degree of reduction depends 
on the comparative affinity of the metal for oxygen. In most 
cases, nitric oxide is one of the products, and in some, the only 
one. It is evolved when copper is acted on by nitric acid mod- 
erately diluted. If the operation be performed in the open air, 
the deutoxide of nitrogen which is evolved instantly combines 
with oxygen and produces nitrous acid, which appears in dense 
red fumes ; but if it be performed in close vessels, and in a re- 
tort the beak of which is plunged under water, the production 
of red fumes only lasts till the oxygen of the air in the vessel is 

* We have witnessed several cases of fainting and spasms in young per- 
sons after inhaling the exhilarating gas, and would never advise anyone to 
venture upon this dangerous experiment, but under the direction of a prac- 
tical and experienced chemist ; and we might add also with a physician near 
at hand. 

353. Its power of supporting respiration. Effects on the human system. 

354. Synonymes. How produced from nitric acid ? 



136 



NITROGEN. 




consumed ; after which, the nitric oxide comes over very rapidly, 
and may be collected under an inverted bell glass filled with 
water. 

Fig. 66. 355. Let some copper filings be 

put into a retort, (Fig. 66,) and nitric 
acid be poured in at the tubulure ; 
place a lamp under the retort, the beak 
of the latter being immersed in water 
below the perforated shelf which sup- 
ports the inverted bell-glass. A vio- 
lent action takes place between the 
copper and nitric acid, and the red 
fumes of nitrous acid, fill the retort 
and pass over into the pneumatic tub 
where they are absorbed by the wa- 
ter; after this, the oxygen in the re- 
tort being consumed, a colorless gas appears, which does not unite with wa- 
ter, but ascends into the bell-glass taking the place of the water with which 
it had been filled. This is the deutoxide of nitrogen, or nitric oxide. 

356. Physical and chemical properties. It is colorless ; its 
specific gravity is 1.04, and it is sparingly absorbed by water. 
When oxygen, either alone, or in mixture with other gases, is 
admitted to a jar containing nitric oxide, brownish-red fumes of 
nitrous acid vapor appear; these are immediately absorbed by 
water. Nitric oxide forms feeble combinations with alkalies 
and alkaline earths ; but as it has no action on blue test paper, 
it cannot be considered an acid. It supports the combustion of 
charcoal and phosphorus, which burn brilliantly in it ; extin- 
guishes a candle and burning sulphur. Hydrogen does not ex- 
plode with it, but the mixture burns with a brilliant flame, of a 
a greenish white color. In all cases of combustion in this gas, 
the combustible becomes oxidized, and nitrogen gas is liberated 
from the deutoxide. It is irrespirable on account of its causing 
a spasmodic closing of the glottis. It is partially decomposed 
by a red heat, or by a succession of electric sparks. Iron 
filings attract part of its oxygen and convert it into the protoxide. 
Potassium, when heated in it, takes all its oxygen and liberates 
its nitrogen, and therefore affords an accurate mode of analyzing 
this gas. 

357. As red fumes of nitrous acid, which are absorbed by water, are al- 
ways produced when nitric oxide is mixed with atmospheric air, this pro- 
perty of nitric oxide is made use of in eudiometry, or the analysis of air, in 
order to ascertain the proportion of oxysren. As in two volumes of nitric ox- 
ide, a volume of nitrogen is combined with one volume of oxygen, (occupying 
the same bulk as if merely mingled,) — to convert this nitrous oxide into ni- 

355. Mode of obtaining deutoxide of nitrogen. 

356. Physical and chemical properties. 

357. Eudiometry by means of action of the protosulphate of iron with ni- 
tric oxide. 



NITRIC ACID. 137 

trous acid, one volume of oxygen must be added. Of course, if nitrous acid 
be the product, one third of the deficit produced, would be the quantity of at- 
mospheric oxygen present.* 

358. Hyponitrous Acid. When a mixture of nitric oxide 
and oxygen is confined over mercury, with strong solution of 
potassa, the alkali is gradually neutralized ; the two gases com- 
bining to form hyponitrous acid which unites with the potassa. 
This acid has not yet been obtained in a separate state. It was 
discovered by Gay Lussac. 

359. Nitrous Acid, called fuming nitrous acid. It is very 
volatile, is usually seen in the form of a red vapor, and has, until 
recently, been described as a gas. It is properly a liquid, and 
may be obtained in that form, by heating nitrate of lead to a dull 
red heat. The receivers must be dry, and kept cool with ice or 
snow. The heat decomposes the nitric acid of the nitrate of 
lead, and resolves it into oxygen and nitrous acid. Nitrous 
acid is powerfully corrosive, of an orange color, pungent odor, 
and sour taste. It reddens litmus paper, and when added to 
solutions of the alkalies, seems to be converted into nitric acid, 
for the resulting salt is a nitrate, and not a nitrite. It boils at 
82° Fahrenheit, and evaporates with very great rapidity, when 
exposed to air. When once mixed with air or other gases, it 
cannot be again liquefied without great pressure or intense cold. 

Nitrous acid can be obtained in the form of vapor, by mixing two meas- 
ures of deutoxide of nitrogen, with one of oxygen, in a glass vessel which 
has been dried and exhausted of air. The vapor cannot be kept over mer- 
cury, for it parts with oxygen to the metal ; nor over water, for the liquid 
absorbs it. It unites with water in all proportions. A very weak solution 
is pale blue ; as more of the acid is gradually added, the solution passes 
through several shades of green and at last becomes orange colored, like the 
dry acid. It is supposed that water at first decomposes nitrous acid, resolv- 
ing it into nitric and hyponitrous acids, and that the blue tint is due to the 
latter. After the water becomes saturated to a certain point, this decom- 
position ceases, and the nitrous acid begins to dissolve unchanged. At this 
period, the red color of the nitrous, with the blue of the hyponitrous acid, 
produces the green. At last, the quantity of nitrous acid is such, that its 
color predominates over, and hides the other color entirely. 

360. Nitrous acid parts, rapidly, with its oxygen to combusti- 
ble bodies, metals, &c, oxidizing some with such rapidity as to 
set them on fire. It is commonly reduced to deutoxide of nitro- 
gen ; but in some cases of violent action, it is totally deprived 

* For a description of Dr. Hare's apparatus for analyzing atmospheric 
air by means of nitric oxide, see Chemistry for Beginners, page 99. 

358. Hyponitrous acid. 

359. Nitrous acid. How obtained in the liquid form. Properties. Ob- 
tained in the form of vapor. Union of this acid with water. Changes of 
color in its solution. 

360. Inflammable nature of nitrous acid, and decomposition. 

12* 



138 



NITRIC ACID. 



of oxygen ; and in others, it is reduced to protoxide of nitrogen 
It is totally decomposed by a red heat. 

361. Nitric acid is known ia commerce under the name of aqua for iis. 
There are two kinds, the single, and double; the latter being twice as strong 
as the former. This acid is procured by mixing nitrate of potassa, or nitre, 
commonly called salt-petre with strong sulphuric acid, and distilling the 
mixture. The proportions differ in different manufactories, and the quali- 
ties of the acid obtained, vary accordingly. The least quantity of sulphuric 
used, is half the weight of the nitric ; the largest, is an equal weight. 

Fig. 67. Experiment. Nitric acid 

on a small scale, may be pro- 
cured with the apparatus 
here represented ; a is a re- 
tort (Fig. 67.) containing 
pounded salt-petre and sul- 
phuric acid ; 6, is a receiver 
communicating with the ves- 
sel c. The lamp, d, serves 
for heating the retort ; the 
stands, with sliding rings, e e, 
support the retort, lamp, and 
receiver. 

Rationale. Sulphuric acid 
decomposes salt-petre (ni- 
trate of potassa,) by uniting 
with potassa ; the nitric acid 
being liberated passes from 
the retort into the receiver 6, and from thence into the bottle, c, and is ab- 
sorbed by water, of which the bottle contains a small portion. On examin- 




ing this water it will be found to be weak nitric acid. 
Fig. 68 



Those who manufac- 
ture nitric acid for pur- 
poses of commerce, make 
use of large iron retorts 
set in brick work (Fig. 68) 
and communicating with 
receivers made of earthen 
ware, furnished with stop 
cocks, the last of which 
has a safety tube commu- 
nicating with a vessel of 
water. 

362. The theory of the 
operation in the manufac- 
tory of nitric acid, is ob- 
vious. Nitre is a com- 
pound of nitric acid and potassa, the sulphuric acid being added, combines 
with the potassa, and forms sulphate of potassa, excluding the nitric acid, 
which being vaporized by heat, is condensed in cool receivers. 




361. Common name of nitric acid. How procured. Exp. Rationale. 
Manufacture of nitric acid for commerce. 

362. Theory of the operation in the manufacture of nitric acid. 



NITROUS ACID. 139 

363. Nitric acid may be formed directly, for the purpose of 
demonstrating its composition synthetically, by passing electric 
sparks through a mixture of oxygen and nitrogen gases confined 
over a solution of potassa. It is believed that a portion of the 
native nitrates owe their origin to the formation of nitric acid 
from the elements of air, by the electric discharge during 
thunder storms; this acid being carried to the earth by the rain, 
acts on the oxides and carbonates with which it comes in 
contact. 

364. Physical and chemical properties. Pure nitric acid is col- 
orless and transparent. It is commonly found of specific grav- 
ity 1.42. It gives off* white fumes when exposed to moist air; 
unites with water in all proportions with the evolution of heat ; 
is sour to the taste, reddens litmus paper and combines with 
salifiable bases to form neutral salts. It attracts watery vapor 
from the air. Its affinity for water enables it to melt snow very 
rapidly, by which liquefaction, great cold is produced. Nitric 
acid becomes red and fuming, by much exposure to light ; for 
that agent decomposes it, resolving it into oxygen gas, which is 
evolved, and nitrous acid which gives the color. Deutoxide of 
nitrogen also decomposes nitric acid, taking part of its oxygen ; 
by which process the nitric acid and the deutoxide are both 
brought to the state of nitrous acid. By red heat it is totally 
decomposed into oxygen and nitrogen gases. It also readily 
parts with oxygen to most bodies which have an affinity for it, 
and is, therefore, a very powerful oxydizing agent. For this 
reason it increases the combustion of red hot charcoal ; and al- 
so converts sulphur and phosphorus into sulphuric, and phos- 
phoric acids. It oxidizes tin, copper, iron filings, powdered zinc 
and some other metals, producing violent action. 

Animal and vegetable substances are powerfully attacked by 
this acid, and some of them, such as volatile oils, are set on fire 
by the rapid oxidation, It stains the skin yellow, destroying the 
cuticle, and causing deep ulceration if not speedily removed. 
The caustic power of nitrate of silver, (lunar caustic,) is due to 
the acid which enters into its composition ; and the acid is oc- 
casionally substituted for the salt, as a caustic. In all these 
cases, the nitric acid is deprived of a part of its oxygen, and is 
reduced either to nitrogen, or one if its oxides. 

365. The salts of nitric acid, called nitrates, possess the 

363. Nitric acid formed by electricity. Supposed origin of some of the 
native nitrates. 

364. Physical and chemical properties of nitric acid. Decomposition by 
light. By deutoxide of nitrogen. By heat. Why a powerful oxidizing 
agent. Its effect on animal and vegetable substances. 

365. Salts of nitric acid. 



140 



NITROGEN. 



power of imparting oxygen to other bodies by the aid of heat, 
and are therefore known as deflagrating salts. 

We shall consider them more fully under the head of salts. 

366, The most delicate of all tests for nitric acid is indigo, the blue color 
of which is destroyed by it, and converted into a yellow. The mode of ap- 
plying the test is to dissolve some indigo in cold, dilute sulphuric acid, and 
add enough of the solution to produce a distinct blue color in the separated 
liquor; then drop in a little more sulphuric acid to take away the base with 
which the nitric acid is combined} the nitric acid, being thus set free, acts 
on the indigo. 

367. History. Nitric acid was discovered by Raymond Lully an alchemist 
in distilling a mixture of nitrate of Boloaa and clay. Basil Valentine, in the 
15th century described it as the 'water of nitre. In 1785 Mr. Cavendish of 
England discovered it to be composed of oxygen and nitrogen. 



CHAPTER XV. 

NITROGEN AND ITS COMPOUNDS. 

Nitrogen and Hydrogen, or Ammonia. 

368. Ammonia. 1 nit.=l4> to 3 hyd.=3. Equiv.ll. This is 
a permanent gas, colorless, and transparent, of an irritating and 
pungent odor, and a burning and caustic taste. It is not 
respirable except diluted with air. If inhaled through the 
nostrils, it irritates them, and produces a flow of tears. It is 
used medicinally to neutralize acidity in the stomach, and is a 
powerful tonic and stimulant. 

Ammonia combines with all the acids, neutralizing them and 
producing a distinct class of salts, most of which are crystallizable 
and soluble. When ammoniacal gas is mixed with any gaseous 
acid, as the muriatic, carbonic, &c, dense white fumes appear, 
and the acid and ammonia combine to form a salt, which is depos- 
ited on the vessels as a white powder. Ammonia extinguishes 
burning bodies which are plunged in it. It will not burn in atmos- 
pheric air ; but a small jet of it burns in pure oxygen. When a 
lighted candle is put into it, the flame becomes yellow, and en- 
larged for an instant before it is extinguished, owing to a mo- 
mentary combustion of ammonia. 

Ammonia may be detonated by the electric spark when in mixture with 
oxygen. The products of the detonation are water and nitrogen, with a 

366. Indiffo a test for nitric acid. 

367. History. 

368. Composition and equivalent of ammonia. Physical Properties. Its 
combinations. White fumes of ammonia, how caused ! Effect of ammonia 
on burning bodies. Detonation. Decomposition by electricity and heat. 



AMMONIA. 



14.1 



little nitric acid. It is resolved into nitrogen and hydrogen gases by a suc- 
cession of electric sparks, or by passing it through r^d hot tubes ; and the 
two gases occupy twice the bulk of the ammonia. By adding oxygen to the 
mixed gases and exploding by the electric spark, it is found to be composed 
of one and a half volume of hydrogen to half a volume of nitrogen, conden- 
sed to one volume; or by weight, of 3 equivalents of hydrogen and 1 of ni- 
trogen. Ammoniacal gas is brought to the liquid state by a pressure of 6£ 
atmospheres, or about 97 pounds to the square inch. 

369. The alkaline properties of ammonia are well marked. It 
turns the yellow color of turmeric paper brown ; but as the am- 
monia soon evaporates, the yellow color is restored. Although 
it is a strong alkali, its elasticity favors the decomposition of its 
salts ; so that they are decomposed by any of the fixed alkalies, 
or by the alkaline earths. This fact furnishes means of procur- 
ing ammoniacal gas. Fig. 69. 

370. The materials commonly used are 
hydrochlorate of ammonia, (sal ammoniac) 
and slaked lime. The odor of ammonia is 
perceived as soon as they are mixed in a 
mortar. The proportions used are equal 
weights of the two articles. On heating 
this mixture in a glass retort (Fig. 69.) 
the gas comes over abundantly mingled 
with watery vapor. To separate the lat- 
ter, there should be an intermediate re- 
ceiver containing fragments of caustic 
potassa. or chloride of calcium. If the" 
latter is used, some of the gas will be! 
absorbed as well as the watery vapor. I 
The dried gas should be collected over" 
mercury. Rationale. The lime combines with hydrochloric acid, and the 
ammonia passes off in gas. 

The gas of ammonia has a 
powerful affinity for water. Its 
solution is "aqua ammonia" and 
" spirits of hartshorn." It is the 
form under which ammonia is 
used in the operations of a labo- 
ratory. Aqua ammonia is ob- 
tained by passing a stream of the 
gas into distilled water. 

Exp. The retort, (Fig. 70) con- 
taining hydro-chlorate of am- 
monia and lime is subjected to 
heat ; ammoniacal gas rises, and 
is received in a vessel containing 
cold water, by which it is rapidly 
absorbed. 




Fig. 70. 




369. Its alkaline properties. Liquefaction of ammonia. Decomposition 
of its salts. 

370. Exp. Mode of obtaining ammonia. Proof of its affinity for water. 



U2 



HISTORY OF AMMONIA. 




The solution is transparent and colorless. It is lighter than water. If 
exposed to the air, it absorbs carbonic acid, and is converted into bi-carbon- 
ate of ammonia. A very common and convenient method of obtaining the 
gas is by heating the solution in a retort. 

Exp. The retort a, (Fig. 71,) contains liquid ammonia 
which being heated by the lamp i, ammoniacal gas evolves, and 
as it is lighter than air, it rises and takes its place in the 
Upper vessel. 

The affinity of ammoniacal gas for water may be furthei 
shown by letting a small quantity of it escape into moist air, 
where on account of its union with aqueous vapor it will 
cause a cloudy appearance. If a piece of ice be passed into 
ajar of this gas, it is liquefied by it immediately; and the 
gas disappears, being absorbed in the water produced by the 
melted ice. 

Smelling bottles are filled with some salt of ammonia mix. 

4§|p L ed with a fixed alkali, to develope the ammoniacal gas. 

The usual materials are carbonate of ammonia, and carbon- 
Igjjjijjj £— ^ ate of soda or potassa ; for the tendency of the fixed alkalies, 
to form fet'-carbonates, enables their neutral carbonates to decompose car- 
bonate of ammonia. The odor is improved by the addition of some fragrant 
oils or spices. The salts of ammonia are inodorous, except the carbonate. 
But they are easily detected by the action of heat, and by the development of 
the odor of ammonia on adding a fixed alkali. Free ammonia may be also 
detected by the white fumes formed on the approach of a rod dipped in hy- 
drochloric acid ; and by its temporary action on moist turmeric paper. (See 
IT 369.) 

371. Nitrogen and hydrogen gases cannot be made to combine 
directly ; but in their nascent state, or at the instant in which 
they leave other combinations, they then unite, and form am- 
monia ; this is always one of the products when animal matter 
undergoes decomposition, either spontaneously or by means of 
heat. 

History. Ammonia was long known as volatile alkali, spirit 
of sal ammoniac, hartshorn, &c. Dr. Priestly called it alkaline air. 
This gas was first procured from sal ammoniac (or salt of am- 
monia,) a salt obtained from the temple of Jupiter Ammon, in 
Lybia, to which is referred the origin of the name. 

372. Hydrochlorate, or Muriate of Ammonia. This salt, com- 
monly called " sal ammoniac" is obtained by saturating hydro- 
chloric acid with ammonia or its carbonate. Its chemical 
equivalent is 63 ; it being constituted of 1 mu. acid 37 add 1 
am. 17, add 1 water 9=63. 



Aqua ammonia. How obtained ? Properties of this solution. Effect of 
this gas upon ice. Smelling bottles. Tests for the salts of ammonia. 

371. In what state nitrogen and hydrogen unite. History. 

372. Hydrochlorate of ammonia. 



CHLORIDE OF NITROGEN. 



143 




Fig. 73. 






M, 



373. Exp. 1st. Into one retort a, Fig. 72. 

(Fig. 72.) put a small quantity of hy- 
drochloric acid, and into another a, li- 
quid ammonia : from each liquid gases 

will be evolved, and passing into the 

cylinder unite and form dense white 

fumes, which at length settle in solid 

concretions on the inner surface of the 

glass cylinder; this precipitate is hy- 

dtvchlorate of ammonia. 

It may be formed directly by mixing Jl 

equal measures of ammoniacal and r f 

hydrochloric gases. 
'Exp. 2d. Let A and B, (Fig. 73.) be two 

flasks with bent tubes containing the gases which 

meeting in the bottle C, are condensed, and form 

hydrochlorate of ammonia. 

374<. Nitrate of Ammonia is composed 

of 1 atom of nit. 1 of am. and 1 of water. XL 

It is readily formed by saturating nitric ( jj j 
acid with carbonate of ammonia. TheV_y 
solution affords crystals by evaporation. 
If evaporated at 100° Fahrenheit, the crystals are large, striated 
prisms. If at 212° Fahrenheit, the crystals are fibrous. And at 
300°, no regular crystallization takes place. This salt in any 
form, is deliquescent. It dissolves in water so rapidly as to pro- 
duce great cold, which is increased if ice or snow be substituted 
for water. Heat decomposes this salt at about 400° Fahrenheit. 
Water and protoxide of nitrogen are the products. Suddenly 
heated to 600°, it explodes violently, forming water, nitrous acid, 
deutoxide of nitrogen, and nitrogen. The tendency which the ele- 
ments of the acid and alkali have to form other compounds, and the 
volatile nature of those compounds, will account for the explosion. 
375, Chloride of Nitrogen. 4 Chi. 144 added to 1 Nit. 14= 
158 ; this substance from its composition may properly be called 
quadro-chloride, having four measures of chlorine. Chlorine does 
not combine with nitrogen, when both are in the gaseous state ; 
but if one of these gases is in the nascent state, it will unite with 
the other, if present. Chloride of nitrogen is the most explosive 
compound known, and is exceedingly dangerous. It is exploded 
by a gentle heat, by slight friction, by agitation, and by the con- 



373. Exp 1st. Exp. 2d. 

374. Composition of nitrate of ammonia. How formed. Crystals. Its 
deliquescence. Action of heat. Cause of explosion by heat. 

375. Composition and equivalent of chloride of nitrogen. In what state 
chlorine combines with nitrogen. Explosive nature of chloride of nitrogen. 
Manner of transferring it. Cause of its ready decomposition. Violent ex- 
plosion, and products of the detonation. 



144 



CARBON. 



tact of many combustible substances ; as a rod dipped in olive 
oil produces detonation the instant of contact. 



<§> 



Fig. 74. The experiment should be made on a globule no larger than 
a mustard seed, which should be placed at the bottom of a deep 
leaden vessel, the water will be dispersed, and the vessel, per- 
haps, rent. The manner in which this yellow oil-like fluid is 
transferred from one vessel to another, is by drawing it into a 
glass syringe (Fig. 74.) having a pointed orifice, and a copper 
wire with a bit of tow wound closely round it for a piston ; thus 
a globule of very small size may be drawn into the tube, and de- 
posited in the vessel prepared for the detonating experiment. 
The facility with which the decomposition takes place, is due to 
the small affinity of chlorine and nitrogen, and their strong ten- 
dency to resume the gaseous form; and the great violence of the 
explosion, is of course, the result of their immense expansion in 
passing from the liquid to the aeriform state. The products of 
the detonation, are chlorine and nitrosjen gases. This experi- 
ment should never be made without strong gloves and glass 
I , masks. Its discoverer, Mr. Dulong, received a severe wound, 
// in experimenting with it ; and Sir Humphrey Davy had his eyes 
^y^ seriously injured in the same manner. 

376. Bromide of Nitrogen. This substance has similar proper- 
ties to the chloride of nitrogen, and may be formed in a similar manner. 

377. Iodide of Nitrogen. This is a black powder, obtained by pouring a 
solution of ammonia on iodine. It is very explosive : but as one of the con- 
stituents is naturally a solid, the explosion is not quite so readily produced, 
nor so violent, as that of the chloride. It is resolved by the detonation, in- 
to nitrogen gas and vapor of iodine. The iodide of nitrogen is supposed to 
consist of 3 equivalents of iodine=372 added to 1 nitrogen 14=386; and 
may properly be termed, a Teriodide of nitrogen. 



CHAPTER XVI. 



CARBON. 



378. Equiv. 



j* 



c ( 3.05 Water =1 

^-^ | 6.12 Hyd. = 



vol. 100. 
weight 6. $ "*" 6 "l 6.12 Hyd. 

Vegetable and animal bodies consist, essentially, of car- 
bon, oxygen, hydroge?i, and sometimes nitrogen. Many of them 
contain, also, several alkaline and earthy salts, and siliceous mat- 



376. Bromide of nitrogen analogous to the chloride. 

377. Properties and constitution of iodide of nitrogen. 

378. Essential constituents of vegetable and animal bodies. Accidental 
components. Mineral substances most abundant in the bark of vegetables. 
Products of the combustion of organic bodies when burnt in the open air. 
Different products when air is excluded. Volatile products of destructive 
distillation. Charcoal. 



CARBON. 145 

ter, which are considered as accidental rather than necessary- 
components. Growing vegetables derive their mineral substan- 
ces from the soil in which they grow, and these are found more 
abundant in the bark where the circulating vessels are situated, 
than in the wood. When organic bodies are heated in the open 
air, the atmospheric oxygen combines with carbon, to form car- 
bonic acid 5 and with hydrodgen to produce water ; and the pro- 
ducts of the combustion, being essentially gaseous, or very vola- 
tile, are dissipated, forming that very complex mixture of gases 
and vapors, called smoke. The alkaline and earthy salts, and 
siliceous matter not being either combustible or volatile, remain 
on the hearth, constituting ashes. 

But the results are quite different, when air is excluded. The 
organic matter is then decomposed by the agency of heat, and 
most of its elements re-combine in various forms. The volatile 
products of this process, (called destructive distillation,) are ex- 
ceedingly complicated. Among them, are impure vinegar, call- 
ed pyroligneous acid ; and acid and fetid oil, to which the name 
empyreumatic oil has been given j carburetted hydrogen or illu- 
minating gas j carbonic acid, ammonia, and watery vapor. The 
oxygen contained in these products, is that which belonged to 
the composition of the organic matter ; and as this is never 
sufficient for the complete oxidation of the carbon and hydrogen, 
a large proportion of the former remains after the experiment. 
This, together with the ashes, constitutes charcoal. 

379. There are several varieties of charcoal, of very differ- 
ent degrees of purity, but all deriving their common character- 
istics from the combustible element, carbon. 

Lamp-black is one of the purest of the common varieties. It is obtained 
by burning refuse oils and resinous matters in chambers hung with coarse 
matting. The smoke deposits free carbon upon the matting, whence it is 
swept off and collected. 

Ivory-black, is an animal charcoal, and is obtained by heating bones ex- 
cluded from air. It contains more earthy matter than vegetable charcoal, 
and is therefore more impure ; but is best for some purposes. The ashes 
it contains, are principally phosphate and carbonate of lime, which consti- 
tuted the hardening matter of the bone. The ivory-black obtained in this 
manner, is that usually met with in commerce. The real ivory-black is ob- 
tained from ivory. 

All the varieties of pit coal, or mineral coal, are carbon, more or less im- 
pure ; and are supposed to be derived from the spontaneous decomposition 
of vegetable matter. Some of them burn with flame, on account of their 
containing bituminous matter. Sulphur is a very frequent ingredient ; and 
the matter of ashes abounds in them. The ashes of mineral coal, however, 

379. Varities of charcoal. Lamp-black. Ivory-black. Mineral coal. 
Its origin. Why some kinds burn with flame. Difl'erence in the ashes of 
mineral and vegetable charcoal. Anthracite. Plumbago. Coke. 

13 



146 



DIAMOND. 



differ from those of vegetable charcoal. The greater difficulty of igniting 
them, is chiefly owing to their greater compactness and density. 

One of the densest and purest varieties of mineral coal, is Anthracite, 
which contains more than 90 per cent, of carbon. Plumbago, or black lead, 
is carbon combined with a very small proportion of metallic iron. Its com- 
position is variable. Coke, is a very dense and impure variety of carbon, 
obtained by the distillation of bituminous coal. The leading object of the 
distillation, is the furnishing of gas for illumination, which is evolved in 
large quantity. Coke is the residual product. It is exceedingly difficult of 
combustion, but when burning in a blast furnace, gives an intense heat. 
Mixed with wood charcoal, it is largely used in smelting iron ores, and other 
metallurgic operations; and its importance is such that coal is frequently 
distilled for the sake of the coke, though the gas be wasted. 

380. Carbon in its purest form, as obtained artificially, may 
be made by passing the vapors of alcohol, ether, and the vola- 
tile oils, through porcelain tubes, heated red hot. 

The purest native variety of carbon, is the diamond, which is 
chrystallized carbon. Many attempts have been made to make 
diamonds, by fusing and by crystallizing carbon, but without 
success. It resists fusion, even in the intense heat of a power- 
ful galvanic apparatus, and no menstruum has been found to 
deposit it in crystals. The diamond is the hardest body known. 
It is generally colorless, but sometimes tinted. It has a highly 
crystaline structure, its primitive form is an octahedron. It is 
a most powerful refractor of light, to which, with the angular 
forms into which it is cut, it gives its brilliant play of colors, 
called its water. Newton conjectured the combustible nature 
of the diamond, on account of its great refractory power, before 

any proof of this property had 
been obtained. It may be con- 
sumed by an intense heat in 
the open air, or by heating it 
strongly with nitre. But the 
most brilliant mode of burning 
diamonds, is in an enclosed por- 
tion of oxygen gas, acted upon 
by a jet of hydrogen. 

Exp. The figure (Fig. 75,) repre- 
sents a glass globe, having fitted to 
its neck, a copper cap, with an appa- 
ratus into which a stop cock is screw- 
ed, and from which a jet-pipe, a, pas- 
ses up into the globe. Above this 
pipe, are two wires, c c, one of which 
is attached to the jet-pipe, the other 
passes through an insulating glass 




380. How may carbon be obtained nearly pure ? Crystalized carbon. 
Properties of the diamond. Exp. showing the combustion of a diamond in 
oxygen gas. Product of the combustion of diamond in oxygen gas. Size 
and value of diamonds. 



CHARCOAL. 14)7 

tube, to the outside of the apparatus, where it terminates at a. At the end 
of the jet-pipe, is a small platinum grate. On this, the diamond is plac- 
ed, in such a situation, that the stream of hydrogen which issues from 
the jet, plays upon it, and not on the platinum. The lower part of the ap- 
paratus, has in its side, an aperture, to which is affixed a tube with a stop- 
cock; and with this is connected a bladder filled with hydrogen gas. 
When the apparatus is used, the glass globe is removedfrom its stand, placed 
on an air pump, exhausted of air, and then filled with oxygen gas ; after 
which it is again screwed to the stand. The wire d, is then connected 
with the conductor of an electrical machine by means of a chain wire ; a 
discharge of electrical sparks is then to pass between the wires cc. A stop 
cock being now opened, hydrogen gas being pressed from the bladder, issues 
through the jet-pipe a, and the diamond is heated to a white heat ; after 
which, it takes fire and consumes. 

The product of the combustion of the diamond in oxygen 
gas, is carbonic acid, which is the same as that arising from the 
combustion of pure charcoal. The most splendid diamonds 
have been found in the East Indies, and in Brazil. They are 
esteemed the most valuable of all gems. Some few have been 
found as large as a pigeon's egg ; these are considered as of 
immense value. 

381. There are three modes of making wood charcoal. 1st. The most 
complete process is that used by manufacturers of gun powder, who require 
very pure charcoal. The process consists in distilling the wood in cylin- 
drical retorts of cast iron. 2d. The ordinary wood charcoal for fuel, 
is prepared by covering a pile of wood with earth, so as nearly to exclude 
air, and then set it on fire at the bottom. The combustion is slow, as but 
little air is admitted ; but in time the volatile parts are driven off and car- 
bon remains. 3d. For chemical experiments, charcoal should be prepared 
by charring wood under sand or melted lead to exclude all the air. 

382. Carbon, or charcoal in its purest form, is black, brittle, 
pulverulent, unaltered by the action of air and moisture at com- 
mon temperatures, and not affected by heat, even the most in- 
tense, when air is excluded. It is not volatile, is infusible and 
insoluble ; is not attacked by alkalies, nor, at commom tempera- 
tures, by any acid. Its specific gravity is said to be greater 
than that of diamond ; wood charcoal, on account of its porosity, 
floats awhile on water, but sinks as soon as its pores are filled 
with the fluid. Charcoal is an excellent conductor of electricity, 
but a very bad conductor of heat, especially when powdered. 

Charcoal has a remarkable antiseptic power, preventing the pu- 
trefaction of meat and vegetables when covered with it in a state 
of powder. On account of its indestructibility it is customary to 
char the end of posts that are to be set in the earth, and the inside 
of the water casks of ships. Grains of wheat, charred by the vol- 

381. Modes of preparing wood charcoal. 

382. Properties of carbon. Antiseptic property. Valuable as a dentii- 
fice. Effect in the decolorization of liquids. 



148 CHARCOAL. 

canic eruption which buried Herculaneum inA.D. 79, were found 
perfect, eighteen centuries afterwards ; and knife handles recent- 
ly made in England and sold as antiques, at a high price, were 
manufactured from charred stakes driven into the bedof the Thames 
to prevent the passage of the Roman army, under Julius Caesar. 
Finely powdered charcoal is an excellent dentrifice, especially as 
the extreme hardness of its particles gives it a great polishing 
power ; It removes coloring matter from liquids of vegetable ori- 
gin ; thus dark colored wines and other liquors are filtered 
through it. The decoloring power is greater in animal, than in 
vegetable charcoal, on account of the greater quantity of earthy 
salts contained in the former. 

383. Charcoal absorbs gases and vapors. This is a mechani- 
cal effect, depending on the porosity of the charcoal. Of the 
different gases, it absorbs different quantities, dependent on 
the relative elasticity of the gases; the least elastic, and there- 
fore most easily condensible gases, are absorbed in the greatest 
quantities. Vapors are, therefore, more absorbable by charcoal, 
than gases, and liquids, still more than vapors. The gases will 
be given off by heating the charcoal. 

Fresh charcoal from box-wood, according to Sassure's experiments, ab- 
sorbed in 24 or 36 hours, — 

of Ammoniacal gas, 90 times its bulk. 

of Sulphurous acid gas, 65 " 

of Carbonic acid gas, 35 " 

of Oxygen gas, 9.42 " 

of Nitrogen gas, 7.05 " 

of Hydrogen gas, 1.75 " 

An application of the absorbing property of charcoal is made by using it 
in a powdered state for removing putrescence from meat which has been 
kept too long, also for cleansing docks, vessels &c. Bad water by being 
filtered through it may be made pure. 

384. Charcoal is highly combustible in air, or oxygen gas ; in 
the former, the combustion is slow, in the latter, brilliant, with 
emission of sparks. In either case, and in all other examples of 
the direct oxidation of carbon, the product is carbonic acid gas. 
If pure, the charcoal is consumed without residue. Charcoal is 
also oxidized by being heated with nitric acid ; but the nitrates, 
chlorates, and some other salts, yield their oxygen to it, very 



383. Absorbing property. On what the absorbing power depends. What 
gases most readily absorbed ? Degrees of absorption of different gases by 
charcoal. Application of the absorbing property. 

384. Combustion of charcoal. Product of the combustion. Action of 
charcoal when heated with nitric acid, or with deflagrating salts. Reduc- 
tion of metallic oxides by charcoal aided by heat. 



CAEBONIC ACID. 149 

rapidly, at a red heat, causing the violent combustion, called 
deflagration. Metallic oxides, also, by the aid of heat, are re- 
duced by charcoal to the metallic state, upon which property are 
founded most of the processes for obtaining metals from their 
ores. There are many other processes, both in Chemistry and 
in the arts, in which charcoal is employed as a powerful 
deoxidizing agent. 

COMPOUNDS OF CARBON AND OXYGEN. 

3S5. Carbonic Acid Gas. 1 Car. 6 to 2 ox. 16-22. 

This gas is constantly found in the atmosphere, being gene- 
rated by combustion, respiration, and many other processes. It 
is contained also in many solid mineral bodies ; thus chalk, mar- 
ble, Iceland spar, and limestone, all consist of the same compound 
of carbonic acid and lime, in different degrees of purity. This 
is the first gas that was distinguished from common air ; its 
discovery opened a new field of investigation, that of the elastic 
fluids, which has changed the aspect of pneumatic chemistry. 

The first steps towai-ds its discovery, may be traced to the Alchemist 
Van Helmont, who observed that calcareous stones sometimes yielded an 
air, to which he gave the name of gas. Hales afterwards asserted, that 
this sort of air was an essential part of these stones ; and he attempted to 
ascertain in what proportion it existed in them. Dr. Black, in 1775, dis- 
covered that this air was capable of being absorbed by lime and the alkalies, 
of neutralizing them, and causing them to effervesce with acids. Priestly 
studied its properties with much care, and the English Chemists usually 
ascribe to him the honor of its discovery. But the French assert that their 
countryman Lavoisier first determined the proportion of its constituent 
parts, and understood its nature. It appears that both Priestly and Lavoi- 
sier were at the same time engaged in studying and experimenting upon 
carbonic acid gas, and publishing in their respective countries the results 
of their investigations. 

386. Carbonic acid gas was at first named fixed air, on account 
of its remaining in a fixed state in stones and rocks ; it has been 
called aerial acid, chalkly acid and gaseous oxide of carbon. It 
received its present name on the reformation of the chemical 
nomenclature. 

387. It may be obtained by burning pure charcoal in oxygen 
gas, or by exposing almost any of its numerous and abundant 
combinations with the metallic oxides, to a strong red heat, in 
an iron retort. 

Exp. 1st. The easiest method of obtaining it is to pour one of the 



385. Composition of carbonic acid gas. Where found ? Importance of 
its discovery. History. 

386. Synonimes. 

387. Modes of obtaining carbonic acid gas. Exp. 1st. Exp. 2nd. 

13* 



150 



CARBONIC ACID. 



F 



stronger acids, (as the hydrochloric) in a dilute state, upon small fragments 
of marble or other carbonate, in a flask or stopped glass retort. The hydro- 
chloric acid unites with the lime of the marble, forming hydrochlorate of 
lime. The liberated carbonic acid gas may be collected over mercury, or 
over water in the usual manner ; or, as it is much heavier than air, it may 
be received in a dry glass bottle or jar, standing with its mouth upwards ; 
in this case, the tube proceeding from the flask must be bent twice at right 
angles, and reach quite to the bottom of the receiving vessel. 

Fig. 76. Exp. 2d. Thus, into the double necked bottle, 

^-y here represented, (Fig. 76,) put fragments of mar- 
ble, and pour through the funnel diluted hydro- 
chloric acid ; effervescence immediately ensues, 
and the disengaged carbonic acid gas, filling the 
bottle, passes out through the bent tube a, into 
the jar b ; and on account of its being heavier, 
crowds out the atmospheric air which the jar 
contained. When the jar is full, a lighted taper 
will be extinguished, if held just within its mouth. 
3S8. This gas is transparent, colorless, 
tasteless, inodorous, and highly elastic ; 
Its specific gravity is above 1.5 ; it extin- 
guishes burning bodies, and destroys the 
-life of animals immersed in it ; these ef- 
fects are not due to the mere absence of oxygen, for they take 
place even when some oxygen is present. Thus charcoal, wood, 
candles, and other carbonaceous substances, are extinguished 
before the oxygen is consumed, by reason of the mixture of the 
latter with the carbonic acid, which is produced in the combus- 
tion. And hence persons are often suffocated by pans of burn- 
ing charcoal in apartments not sufficiently ventilated. The un- 
wholesome effect of crowded assemblies, is partly due to the 
carbonic acid produced by respiration. This gas acts on the 
system as a narcotic poison. 

It is often found in wells, pits, and caverns, beinp; generated 
there by the spontaneous decomposition of organic matter, or of 
earthy carbonates. Before descending into such places, it is 
proper to let down a burning candle. If it be extinguished, the 
air is unfit to support respiration. Another test is clear lime 
water, which heroines covered with a pellicle of carbonate of 
lime when exposed to an atmosphere of this gas. It may be re- 
moved in such cases, by letting down buckets containing a mix- 
ture of lime and water, as the lime unites with the carbonic 
acid gas to form carbonate of lime; or it may be drawn up in 
buckets, and poured out like water. 



388. Properties of carbonic acid gas. Its effects on combustion and an- 
imal life. Pans of burning charcoal in close rooms. Air of crowded as- 
semblies. Air of wells, pits, &c. Tests by which the presence of carbonic 
acid gas may be known. How may the gas be removed ? 



CARBOX. 



151 



Fig. 77. 




389. Put into a three necked 
bottle (Fig. 77,) two ounces of the 
carbonate of ammonia, and one 
ounce of orange colored nitrous 
acid, carbonic acid gas will be 
evolved and be visible as it rises 
in a cylindrical jar, htted to the 
bottle. When full, it will press 
out beneath the cover at the top 
of the jar. Let the cover be re- 
moved, and a candle introduced 
within the vessel, and it will be 
extinguished- The gas can be 
drawn off at A ; its current will be 
visible, and it will extinguish a 
burning candle held beneath the 
orifice. It can be drawn like a 
liquid, into a tumbler, (Fig. 78,) 
from whence it may be poured up- 
on a burning lamp which it will 
extinguish. 

Fig. 78. 




390. As water absorbs carbonic acid gas, another mode of re- 
moving it from wells, &c, is to pour down a quantity of water. 
Animation, when suspended by the effect of this gas, has been 
restored, in some cases, by dashing cold water over the patient. 
Water absorbs its own bulk of carbonic acid gas, at the ordinary 
temperature and pressure of the atmosphere ; under a greater 
pressure, a larger quantity is absorbed. Thus a pressure of 
two atmospheres causes water to absorb twice its bulk of the 
gas ; three atmospheres, three times its volume, and so on. By 
a pressure equal to thirty six atmospheres, carbonic acid itself 
becomes condensed into a liquid. 

389. Experiment to shew that carbonic acid gas is heavier than atmos- 
pheric air. 

390. Absorption of carbonic acid gas by water. Effect of pressure on this 
absorption. Soda or carbonated water. Describe Dr. Hare's appparatus 
for carbonating water. What takes place when the water is relieved from 
pressure ? 



& 



CARB0KIC ACID. 



By compressing carbonic acid gas over water with a forcing 
pump, the water becomes highly charged with the gas, forming 
what is sold, as soda water, but, in general is merely carbonated 
water. 

Dr. Hare's apparatus for charging water with carbonic acid. 

Fig. 79. 




A, (Fig. 79,) is a condenser fastened into a block of brass furnished with 
a conical brass screw, by means of which, it is easily attached to the floor. 
In this block are two valves, one opening inwardly from the pipe B, the 
other outwardly towards the pipe C. The pipe B, communicates with a 
reservoir of gas which the condenser draws in, and forces through the other 
pipe, into a strong copper vessel containing the water. The carbonated 
water is drawn out by means of a syphon D. When the pressure on the 
water is relieved, the greater part of the gas escapes with effervescence, 
leaving only what the water is capable of holding in solution, at ordinary 
atmospheric pressure. The remainder may be expelled by boiling the wa 
ter or by placing it under the receiver of an air pump, and exhausting th» 
air. 

391. Water which contains carbonic acid gas, has a lively, 
brisk taste, sparkles when poured from one vessel to another 
and changes to red the blue color of litmus paper ; but thclatte. 
effect is only temporary, for the acid soon evaporates and th 

391. Properties of carbonated water. Tests of carbonic acid in wate-« 
Cause of the crust which is deposited when spring water is boiled. 



CARBONIC ACID. 153 

blue is restored. The insipid taste of boiled water is owing to 
its having lost the carbonic acid which spring waters always 
contain. The presence of this gas in water, may be detected 
by mixing it with clear lime, or baryta water ; it becomes milky, 
on account of the formation of an insoluble carbonate of lime or 
baryta. 

Care should be taken to have the alkaline water in excess ; for if the car- 
bonated water predominate, the precipitate is not formed, or is re-dissolved, 
those carbonates being soluble in excess of carbonic acid. On account of 
the latter property, the spring waters of a limestone district, often contain 
carbonate of lime in solution. On boiling, the excess of carbonic acid is 
expelled, the carbonate of lime is deposited, and by frequent repetition, the 
vessel in which it is boiled, becomes lined with a white calcareous crust. 

392. Carbonic acid gas is a product of fermentation. If cider, 
beer, champagne, &c M be put into bottles, and tightly corked 
before the fermentation has entirely ceased, the gas which is 
generated during the remainder of the fermentation, is forced 
into the liquids under a considerable pressure, and gives them 
the effervescent quality or liveliness, which renders them agree- 
able. An overcharge of the gas, expels the cork or bursts the 
bottle ', and this will happen when the liquors are bottled too 
soon. This occurrence often takes place in bottled yeast, which, 
in fermentation, gives off a large proportion of gas. 

393. It has been remarked, (§34-9,) that carbonic acid gas is 
always present in the atmosphere, and that the vegetation of 
plants has an agency in decomposing it and restoring oxygen to 
the air. A small proportion of carbonic acid in the atmosphere 
is favorable to vegetation, by furnishing carbon to the plants ; 
but in too large proportion it destroys vegetable life. It has 
been found that plants are benefitted by being watered with a 
solution of this gas. Carbonic acid combines with the alkalies, 
earths, and most of the salifiable metallic oxides, forming a class 
of salts called carbonates, many of whch occur abundantly as 
minerals, as carbonate of lime in its various forms of limestone, 
chalk, marble, Iceland spar, stalactite, &c. The carbonic is a 
very weak acid, and does not completely neutralize the alkalies j 
therefore all the carbonates are decomposed by hydro-chloric, 
nitric and most other acids, carbonic acid escaping with effer- 
vescence. All the carbonates, except those of ammonia, potas- 
sa, soda and lithia are decomposed by heat. 

394. Carbonic acid is the highest known oxide of carbon. It 
contains in bulk one volume of carbonic vapor and one volume 
of oxygen, condensed into one volume. 

392. Cause of the effervescence and other peculiar properties of ferment- 
ed liquors. Bursting of the bottles containing such liquors. 

393. Decomposition of carbonic acid gas by plants. Carbonates. Why 
easily decomposed 1 

394. Composition of this gas. How proved. 



154? CARBONIC OXIDE. 

Its composition is proved by passing the vapor of phosphorus over a red 
hot carbonate, in which case phosphoric acid is formed and carbon set free ; 
or by passing a succession of electric sparks through the gas, by which 
means it is resolved into oxygen and carbonic oxide ; or by electrifying 
a mixture of hydrogen and carbonic acid when water and carbonic oxide 
will be formed. It is also decomposed by being brought in contact with 
iron filings or charcoal at a red heat ; the iron or charcoal takes half its 
oxygen, converting it into a carbonic oxide. Potassium takes the whole of 
its oxygen ; forming potassa and liberating carbon. 

395. Carbonic acid gas has been liquefied by very powerful compression 
aided by exposure to cold. Mr. Faraday obtained it in this state by disen- 
gaging it from carbonate of ammonia by means of sulphuric acid, in a glass 
tube hermetically sealed, one end being immersed in a freezing mixture. 
The liquid acid was colorless, and floated upon the sulphuric acid and water, 
contained in the tube. The pressure under which this fluid was formed 
was estimated to be equal to that of thirty six atmospheres. A French 
Chemist* who had previously succeeded in liquefying this gas, announces 
that he has also obtained it in a solid state. Its solidification requires a cold 
equal to 100th degree of the centigrade below the freezing point ; and, 
thoush the liquefied gas evaporates almost instantaneously, and with a vio- 
lent explosion, the solid continues some minutes exposed in the open air, 
and insensibly disappears by a slow evaportion. The first instance of a 
gas becoming solid and concrete is so much the more remarkable as it relates 
to a gas, to liquefy which requires the most powerful mechanical action, 
and which resumes with great rapidity its gaseous state when the compres- 
sion is removed. In the liquid state its elastic force is equal to that of gun- 
powder, while in the solid state the spring appears completely broken, the 
new body disappearing by slow evaporation. 

39(5. Carbonic Oxide, Its constituents are, 1 atom of carbon 
with 1 of oxygen— 14 its chemical equiv. It is never formed by 
the direct oxidation of carbon, carbonic acid being always the 
result of that process. Most of the processes for obtaining 
carbonic oxide depend on depriving carbonic acid of half its 
oxygen ; this is easily effected at a red heat, by charcoal and by 
several of the metals. Thus when a mixture of chalk and iron 
filings is heated to a red heat, carbonic acid is driven from the 
chalk ; the hot iron immediately takes a part of the oxygen from 
the carbonic acid and reduces it to carbonic oxide. When char- 
coal is used for this purpose, it is itself converted into carbonic 
oxide. The gas thus evolved may be collected over water. 

Other more easy and elegant processes are founded on the decomposition 
of oxalic acid and its salts by sulphuric acid. Oxalic acid is a crystalizable, 
poisonous, vegetable acid, which like nitric acid is incapable of existing in 
an uncombined state ; so that when not united to a salifiable base it always 

* M. Thilorier. See Silliman's Journal, Oct. 1836 ; and also the same 
Journal for Jan. 1837. Translations from Jlnnales de Chimie. 

395. Pressure under which it was formed. Solidification of carbonic acid. 

396. Composition of carbonic acid gas. How formed. How obtained by 
heating chalk with iron filings ? How obtained by means of oxalic and sul- 
phuric acid. Dr. Hare's apparatus for separating carbonic acid gas from 
carbonic oxide. 



CARBONIC OXIDE. 



155 



contains water. Besides this water necessary to its existence, the crystal- 
ized acid consists of 3 atoms of oxygen and two of carbon. On heating this 
acid or its salt? in a glass retort, with an excess of sulphuric acid, the lat- 
ter takes both water and alkaline base ; the oxalic acid, thus set free, re- 
solves itself into the two gaseous compounds of carbon and oxygen. These 
mixed gases being collected over mercury, the carbonic acid will be speedily 
absorbed by a little milk of lime or solution of potassa, and the carbonic 
acid remain pure. 

Dr. Hare's apparatus for purifying carbonic oxide by lime water* 



Fig. 80. 




The gases being obtained in the manner directed above, they are convey- 
ed by means of the pipe, P, (Fig. 80,) which is supposed to communicate 
with a reservoir of the mixed gases, to the bell glass C, containing lime 
water. The lime water sinks into the lower bell glass, A, as the gases are 
introduced by turning the stop cock communicating with the pipe P. The 
lower pipe D, communicating with the bell glass A, has affixed to it an In- 



IbG CARBONIC OXIDE. 

dia rubber bag ; by pressing this with the hand, jets of lime water are 
thrown into the gas in the bell glass C, until all the carbonic acid having 
united with the lime, the carbonic oxide is left pure, and may now be trans- 
ferred to any receiver by turning the stop cock of the pipe P. 

S97. Carbonic oxide is transparent, colorless and inodorous ; 
it is very sparingly absorbed by water ; its specific gravity is 
0.972. It has neither acid nor alkaline properties, and has no 
effect on lime water. It extinguishes burning bodies, and is ir- 
respirable, being like carbonic acid, a narcotic poison. It is in- 
flammable, burning in contact with oxygen with a pale flame. 
In this, and all cases of its direct oxidation, carbonic acid is the 
sole product. 

Exp. Place an inverted jar over a vessel of carbonic oxide which is burn- 
ing in a jet, as it issues from the tube at the mouth. The inverted jar will 
be filled with carbonic acid gas. The air furnishes another atom of oxy- 
gen=:8, which uniting with the carbonic oxide=14 makes carbonic acid=22. 

The blue flame of carbonic oxide is sometimes seen on the upper part oi 
a charcoal or anthracite fire; the draught of air entering below, the com- 
bustion of the coal there produces carbonic acid, which, in rising through 
the mass of ignited coal, is decomposed and converted into carbonic oxide. 

398. Carbonic oxide gas being mixed with half its volume of 
oxygen gas, the mixture may be exploded by an ignited body or 
by the electric spark, carbonic acid being the product. It may 
also be exploded in a similar manner by mixing it with protox- 
ide of nitrogen. 

By volume, the constituents of carbonic oxide are one measure 
of carbon vapor, and half a measure of oxygen gas, condensed 
into one measure. It was discovered by Dr. Priestly in distil- 
ling charcoal with the oxide of zinc ; but its nature and compo- 
sition was determined by Mr. Cruickshank. 

Carbonic acid with Ammonia, or Carbonates of .Ammonia. 

399. The neutral carbonate of ammonia is a dry white powder, having the 
odor of ammonia, though not in so high degree, and very soluble in water. 
It is never met with in commerce, and can only be formed by mixing one 
volume of carbonic acid gas, and two of ammoniacai gas, both in a perfectly 
dry state, over mercury. Both gases disappear entirely, and the white pow- 
der of carbonate of ammonia is deposited. 

400. The Sesqui* carbonate is the commercial carbonate of ammonia. It 
is procured in an impure state for the purpose of forming hydrochlorate of 

* Latin term, signifying one and a half. 

397. Properties of carbonic oxide. Exp. To prove that carbonic oxide 
is combustible, and that the result of its combustion in the air is carbonic 
acid gas. Blue flame of carbonic oxide seen in coal fires. 

398. Explosive mixtures Avith carbonic oxide. Constitution by volume. 
History. 

399. Neutral carbonate of ammonia. 

400. Sesqui carbonate of ammonia. How prepared. Its properties. 
How is the bi-carbonate of ammonia formed ? 



CARBON WITH HYDROGEN. 157 

ammonia, by heating bones and other animal matter in close vessels. Ani- 
mal matter being composed of carbon, oxygen, hydrogen, and nitrogen, the 
elements are separated by the agency of heat and recombined in other forms, 
one of which is the salt in question. The sesqui-carbonate of the shops, is 
procured by sublimation from a mixture of hydrochlorate of ammonia with 
carbonate of lime. On exposure to the air this salt becomes opake and 
pulverulent, loses its odor and decreases in weight. It is then found to 
have become bi-carbonate of ammonia. Bi-carbonate of ammonia is formed 
as above, by exposing the sesqui-carbonate to the air. It is also obtained 
by passing a current of carbonic acid gas through a solution of the common 
Ci'.bonate. On evaporating the solution, the salt crystalizes. 



CHAPTER XVII. 

Compounds of Carbon with Hydrogen 

401. Carbon and hydrogen possess opposite properties in re- 
spect to their tendency to assume the gaseous form. They have 
a strong affinity for each other, and their compounds are remark- 
able for their inflammable nature. Carbon and Hydrogen form, 
with each other, at least, six definite compounds % 

1. Light carburetted hydrogen gas, consisting of 1 equivalent add to 2. eq. 

2. Olefiant gas, " 2 " " 2. " 

3. Faradav's bicar. hvd. " 6 " " 3. " 

4. « Quadrocarburet, " 4 « " 4. " 

5. Naphtha, « 6 « " 6. « 

6. Naphthaline, " 3 " " 2. " 

Of these, the first two are permanent gases. The fourth is a 
vapor at common temperatures, but a liquid at 0° F ; the third 
and fifth are volatile liquids ; and the last is a volatile solid. 

402, It is to be observed that several of these compounds present a re- 
markable exception to the laws of combination. The second, fourth and 
fifth consist of carbon and hydrogen in precisely the same ratio, that is, one 
equivalent of each element ; yet they are totally distinct in all their physi- 
cal, and most of their chemical properties ; nor have we any right to sup- 
pose that a compound consisting of one proportional of hydrogen and one ot 
carbon would resemble either of them. The constitution of these bodies 
seems to indicate that, for the formation of any specified compound, not 
only must certain proportions be observed in the quantities of the constit- 
uents, but also, that the concurrence of a particular number of atoms is ne- 
cessary. Thus, if we could compel three atoms of olefiant gas to cohere, 
we should probably obtain an atom of Naphtha ; and if two atoms of the 

401. Affinity of carbon and hydrogen for each other. Different forms 
under which they combine. Names and composition of these compounds. 
States in which they exist. 

402, Exception of some of these compounds to the laws of combination. 

14. 



158 FIRE-DAMP. 

same gas were to coalesce, they might form an atom of quadrocarburet. 
The analysis of some organic bodies proves that slight variations in com- 
position, or different modes of combination may produce great differences 
in properties : there is but one other case, that of hydrophosphoric acid, in 
which the laws of combination appear so inexplicable as in the present. 
Until more light is thrown upon the subject, we must be content to attri- 
bute the difference of properties, among bodies containing the same elements 
in the same proportions, to the influence of the mode of combination* 

403. Light Carburetted Hydrogen. The gas is also called sub- 
carburetted hydrogen gas, and bi-hydroguret of carbon. It was 
formerly known as inflammable air, and the air of marshes. It 
can only be obtained, in a separate state, by stirring the mud 
of stagnant pools, and collecting the bubbles of gas as they rise 
in an inverted receiver filled with water. It is formed in such 
situations during the spontaneous decomposition of vegetable 
matter. 

There is a rivulet running through the village of Fredonia, and another 
which passes by Portland Harbor, both in Chautauque County in the State 
of New York, from the waters of which bubbles of light carburetted hydro- 
gen gas are constantly rising. The supply of gas at Fredonia is sufficient 
for lighting the houses of the village, and a gasometer has been constructed 
for collecting it. The light house on Lake Erie at Portland harbor is com- 
pletely supplied with gas obtained from the rivulet above mentioned. The 
origin of the gas in these cases has not been traced. 

404. This gas is colorless, transparent, tasteless, inodorous, 
sparingly absorbed by water, and of specific gravity 0.5555. It 
burns with a yellow flame ; and if mixed with air or oxygen in 
proper proportions, it explodes violently, when touched with 
flame or the electric spark. Whether exploded, or burnt silent- 
ly, the sole products are carbonic acid and water. 

405. Blowers and Fire-damp. Light carburetted hydrogen 
is often generated in large quantities in coal. Sometimes it is 

* Since these anomalies in the laws of chemical combinations began to 
attract the attention of men of science, they have been arranged under 
different heads : as Isomerism, from the Greek isos equal, and meros a part ; 
polymerism from polus many and meros ; and metamerism, according to, and 
meros. Isomeric bodies are those which contain the sarae absolute and re- 
lative number of atoms of the same elements, and have, therefore, the same 
atomic weight ; Polymeric bodies are those which contain the same relative, 
but not the same absolute number of atoms of the same elements, and whose 
atomic weights are consequently unlike. Metameric bodies are those which, 
while they contain the same absolute, and the same relative number of 
atoms of the same elements, yet constitute substances belonging to an en- 
tirely different class of bodies, or a different order of chemical compounds. 
The carburets are therefore polymeric bodies. 

(Rep. of the British Association for 1835, pp. 435, 436.) 

403. Synonymes of light carburetted hydrogen. How formed, and ob- 
tained ? Natural reservoirs of this gas. 

404. Properties. Products of its combustion. 



FIRE-DAMP. 159 

pent up in cavities where it was formed, and, being under great 
pressure, Tushes out with much force, when a cavity is broken 
into ; a reservoir of this description, is called by the miners, " a 
blower." At other times, it issues silently from between the 
layers of coal. In either case, it mixes with the air of the mine, 
constituting the fire-damp of the miners, which, if set on fire, 
explodes with terrible violence, producing a shock which has 
been felt at a distance of several miles. By the explosion of 
the fire-damp, carbonic acid and water are produced; so that if 
it were possible for a miner to escape the effect of concussion, 
he would perish by suffocation in the mephitic gas, which the 
miners call choke-damp. Such explosions were frequent, in the 
British coal mines, till a few years ago ; and the annual loss of 
life occasioned by them, was truly deplorable. It was reserved for 
the genius of Sir H. Davy to discover means for preventing such 
dreadful accidents, and "the fear of them." Davy descended with 
the miners into the region of the fire-damp to obtain specimens 
of the gas. He found by experiments that the most explosive 
mixture was 1 part of gas to about 7 of air ; that 5 volumes of 
air would explode but feebly, and that over 14 volumes of air to 
1 of gas would not explode at all. He also found that the most 
explosive mixture can not be kindled without the heat of flame ; 
that iron at a red heat and even at a white heat will not explode 
it. By means of a little instrument, called the safety lamp, whose 
simplicity is scarcely less admirable than its utility, the miner 
now fearlessly descends into dark caverns filled with combustible 
gases, and lamp in hand safely pursues his daily avocations, un- 
disturbed by the terror of destructive explosions. 

In the course of his experiments, Sir H. Davy assisted by previous dis- 
coveries of Dr. Wollaston, developed some facts respecting the nature of 
flame, a subject which had not previously been well understood, and which, 
as connected with our present subject we shall here introduce. 

Flame is found to be gaseous matter in a state of incandescence, and its 
temperature far higher than any to which solid bodies can be brought. 
This being the case, in order to extinguish flame it is only necessary to 
cool it ; this may be effected by bringing it into contact with a sufficient 
quantity of solid matter which may convey away the heat by means of its 
conducting power. It would follow from this, that the greater the conduct- 
ing power, the less the mass of solid matter necessary to effect the object, 
and vice versa ; and consequently that metals would produce the effect more 
readily than any other bodies, the masses being the same. Some of these 
facts may be readily proved by simple experiments. If the point of a knife, 
or the end of a metallic wire be held very near to the flame of a candle, a 

405. Blowers of mines, Fire-damp, its properties, &c. Choke-damp. 
Observations on the nature of the fire-damp which led to Davy's invention. 
Different temperatures of different flames. Gases kindled by solid bodies 
at different temperatures. Explosive mixture of light carburetted hydrogen 
and oxygen. 



160 



CARBON. 



dark spot will appear on the blaze opposite to the metallic point ; the gas 
in that part being cooled below incandescence by the conducting body. If 
a very small flame be made with a cotton thread, passed through a cork 
shaving, and floating on oil, it will be extinguished by holding over it, and 
in contact with it, an exceedingly small ring of fine iron wire ; a ring of 
glass of the same size, will diminish the flame, and a larger glass ring will 
put it out, the sufficiency of conducting power being compensated by the 
greater quantity of matter. 

Wollaston had observed, that " an explosive mixture cannot be kindled 
through a glass tube so narrow as 1-7 of an inch in diameter," and also 
that the mixture could not be exploded through fine wire gauze, which acts 
on the same principle as longer tubes. Now if a fine wire gauze be held 
upon a common flame, the flame will not pass through the gauze, but will 
appear as if cut off, (See Fig. 81.) On applying a lighted taper above the 
wire gauze, a flame will be produced on the upper surface, which is a con- 
tinuation of the flame below, (See Fig. 82.) The gas of which the flame 
consists, actually passes through the gauze, but is extinguished in its pas- 
sage, bv the cooling power of the wire. 

Fig. 81. Fig. 82. 





Fig. 




Davy's Safety Lamp. (Fig. 83.) A is a cylinder or case 
of wire gauze, having no less than 625 apertures to the 
square inch, with a double top securely fastened to the brass 
rim B, which screws on to the lamp C. The whole is pro- 
tected and rendered convenient for use, by the frame and 
ring D. With this lamp the miner would not be exposed to 
suffocation for want of oxygen, since he would be admonish- 
ed by its becoming extinguished that an atmosphere which 
could not support the combustion of the oil, would not sup- 
port respiration. 

In gas manufactories, spirit ware-houses, and in all places 
where inflammable vapors or gases are likely to be genera- 
ted, as in the examination of foul sewers and drains, where 
artificial light is required, it is obvious that these lamps 
have verv important uses, as well as in the lighting of 
mines. As different flames have different temperatures, it 
will obviously be necessary to vary the texture of the gauze, 
according to the nature of the gas to be extinguished. 
Moreover it is necessary to observe, that some gases, as 
carbonic oxide, are kindled by a solid body at a dull red 
heat ; others require a bright red, or a white heat, to set 
them on fire ; while some are not ignited without the direct 
application of flame. It happens, that light carburetted 
hydrogen requires a higher temperature for ignition than 
any other gas ; this is fortunate, because the wire gauze 
must, necessarily become heated, which would cause the 



CARBON. 



161 



ignition of explosive mixtures, containing other inflammable gases and vapor. 

406. Explosive mixtures, may be made to undergo a sort of slow combus- 
tion at a temperature below that of flame, and consequently without explo- 
sion. This fact may be demonstrated by immersing a small slip of platinum 
foil or wire, heated red hot, into a mixture of light carburetted hydrogen 
and air. The temperature of the heated metal will cause the oxygen to 
combine with carbon and hydrogen, enough heat being evolved by the chem- 
ical action, to keep the wire ignited, but not enough to set the gaseous mix- 
ture on fire. Upon this fact has been founded the 
Jlamckss lamp, (Fig. 84.) A spiral coil of fine platinum 
wire is placed vertically, so as to surround the cotton 
wick and rise a quarter of an inch above it. Some al- 
cohol being put into the lamp, the wick burns and ig- 
nites the platinum wire. In this condition, if placed in 
an explosive mixture, and the wick be extinguished, 
the wire will continue to glow, giving light enough to 
guide the steps of the miner to a place of safety. 

407. It appears that an explosive mixture of any com- 
bustible gas with oxygen, is necessary to the production 
of flame, and that an ordinary flame is a mere shell, 
the interior of which is filled up with gas, which is not 
ignited. This fact may be demonstrated by a few sim- 
ple experiments. 

Exp. 1st. Hold a thin glass tube, o, (Fig. 85,) 
about the diameter of a small quill, and three or four 
inches long, so that its lower extremity shall be im- 
mersed in the flame a, of a large candle, the tube 
making an angle of about 45° with the axis of the 
flame ; a portion of the gas b, from the interior of 
the flame, wijl pass along the tube, and may be set 
on fire at its extremity. 

Exp. 2nd. With a fine pointed glass syringe, gas 
may be drawn from the interior of a common lamp 
flame, and on being gently pressed out, in contact 
with a spirit lamp will burn. 

Exp. 3d. On cutting off the flame with wire 
gauze, and looking down upon it, it will be seen that 
the section is a luminous ring, of which the central part is quite dark. 

Exp. 4th. Place a wooden hoop (Fig. 86,) 
of 6 or 8 inches diameter, and 2 or 3 inches 
broad, upon the water of the pneumatic tub. 
"Within this hoop, pour some sulphuric ether, 
and set it on fire. A large flame will be obtain- 
ed, and it may be shown that combustion is not 
going on in its interior, by passing the hand 
through the water under the hoop, and up into 
the center of the flame, taking care not to touch 
its sides. Considerable heat will be felt, but it 
may be endured for a second or two without 
much inconvenience. 





406. Slow combustion of explosive mixtures without flame. Heated pla- 
tinum immersed in a mixture of light carburetted hydrogen and air. 

407. Experiments showing that flame is a shell, the interior of which 
contains gas not ignited. 

14* 




162 CARBURETTED HYDROGEN. 

408. But though the space within the flame he not in a state of ignition, 
there is oxygen contained in it, the motion of the inflammable vapor through 
the air being sufficient to cause the two to mingle to some extent. That 
oxygen is contained there may be proved by putting in some combustible 
requiring less oxygen than that which constitutes the basis of the flame. 
Fig. 87. Thus if a piece of phosphorus be put in a small wire cage 
at the extremity of a wire bent at right angles, (Fig. 87,) it 
may be passed up under the hoop into the flame ; the water 
will drain off through the cage, the phosphorus will soon melt 
and at last take fire, and be consumed. Thus the inner part 
of the flame is not in a state of ignition, not because oxygen 
is not present, but because it is insufficient to form an explo- 
sive mixture with the inflammable gas. 

409. The luminousness of flames depends in general, on 
the presence of solid matter diffused through them in an in- 
candescent state, and not to their heat. Indeed the colorless flames, such 
as those of hydrogen and strong alcohol, are often hotter than the luminous 
ones; for the solid matter which makes a flame luminous, exerts a cooling 
influence proportionate to its conducting power. Pure hydrogen and oxy- 
gen, if set on fire in a strong glass globe, will give a strong light, because 
of the great compression. Of all flames, the white, containing a due 
proportion of all the rays of the spectrum, is most luminous; the colors of 
the rest are owing to the deficiency of some of the rays, and the consequent 
preponderance of others ; of the colored flames, the yellow is the most lu- 
minous. 

410. The flames of common fires, candles, lamps, &c, consist 
of some of the compounds of carbon and hydrogen ; generally, 
of several mixed together. These gases arise from the decom- 
position which wood, oil, and the other organic matters undergo 
by the action of heat. The carburets of hydrogen, all undergo 
decomposition at some degree of heat, the higher carburets being 
more easily decomposed than light carburetted hydrogen ; the 
carbon and hydrogen burn separately ; and the particles of 
ignited carbon diffused through the flame of hydrogen, give it 
its luminous property. If the quantity of carbon is out of pro- 
portion to the supply of oxygen, a portion of it escapes unburnt, 
and is seen in the form of black smoke, which soon settles of it- 
self, on cold surfaces ; instances of this, are seen in the combus- 
tion of naphtha, oil of turpentine, and bituminous matters. But if 
the quantity of carbon be duly proportioned to the supply of ox- 
ygen, it is all consumed, and there is no smoke, as in the burning 
of strong alcohol. 

408. Is the flame not ignited because there is no oxygen present ? How 
may it be proved that there is some oxygen within the interior of the flame. 

409. Why the least luminous flames are, in general, the hottest. Differ- 
ent colored flames. 

410. Flames of fires, candles, &c. Cause of black smoke. Why there 
is no smoke in the burning of alcohol. 



OLEFIANT GAS. 



Olefiant Gas. 



163 



411. This gas was so called from its oily appearance, when 
combined with chlorine. It is sometimes called hydruret of car- 
bon or percarburetted hydrogen, and is obtained by gently heating, 
in a glass retort, a mixture of one measure of alcohol and three 
of strong sulphuric acid. The gas is freely evolved and is to be 
collected over water. If it be cloudy at first, it must stand some 
time over the water or be agitated with water before use. Ole- 
fiant gas is colorless, tasteless, nearly inodorous and of specific 
gravity 0.97. It is very little absorbed by water, extinguishes 
flame, and does not support respiration. It burns in the air 
with a white flame of greater splendor than any other gas ; and 
when previously mixed with oxygen gas and set on fire, it de- 
tonates with exceeding violence. It is resolved into its elements 
by a succession of electric discharges, and it is more or less 
completely decomposed by passing through heated tubes, ac- 
cording to the degree of heat employed ; a low heat only re- 
ducing it to light carburretted hydrogen, while an intense heat 
entirely separates its elements. 

412. Olefiant gas derived its name from its property of forming an oil-like 
fluid by combination with chlorine. This combination takes place when 
the two gases are mixed, and the presence of light is not necessary to the 
re-action. The compound so formed is properly called hydro-carburet of 
chlorine, but from its volatility and etherial taste and odor is often denomi- 
nated chloric ether. It has a sweet and aromatic taste, boils at 150° F. dis- 
tills unchanged, and is decomposed in passing through red hot tubes. It 
produces a kind of intoxication, more resembling that of protoxide of nitro- 
gen than that of ardent spirits, and has been recommended as a stimulant 
in medicine. It dissolves freely in alcohol, but not in water ; yet the alco- 
holic solution may be diluted to any extent. The solution of chloric ether 
in alcohol may be obtained by distilling a mixture of alcohol and chloride 
of lime ; and it is also formed when chlorine gas is passed into alcohol. If 
hydro-carburet of chlorine or chloric ether be confined under a bell glass 
filled with chlorine, and exposed to the sun, it is decomposed : the free 
chloric combining with its hydrogen, and leaving the carbon and chlorine 
of the compound in combination, constituting perchloride of carbon. 

Bromine and iodine likewise may be brought by indirect methods, into 
combination with olefiant gas, forming the hydro-carburets of bromine and 
of iodine ; compounds bearing a close analogy to the hydro-carburet of 
chlorine. 

413. Bi-carburet of Hydrogen. This according to Faraday is 
a transparent liquid, of an oily appearance having the odor of 

411. Composition of olefiant gas. Synonymes. How obtained. Proper- 
ties. Products of its combustion. Decomposition. 

412. Derivation of the name. Hydro-carburet of chlorine. Combinations 
of olefiant gas with bromine and iodine. 

413. Composition and properties of bi-carburet of hydrogen. Decompo- 
sition. 



164? CARBITRETTED HYDROGEN; 

oil gas and a specific gravity of 0.85. It boils at 186° and 
freezes at 30°. It does not mix with water, but dissolves in al- 
cohol, ether and oils. It burns with a yellow flame giving out 
much soot ; and its vapor explodes with oxygen gas or air. It 
is decomposed by chlorine in the sunshine, and by being passed 
through red hot tubes ; carbon being deposited in each case. 

414. Quadro- Car buret of Hydrogen is a liquid at zero, but 
boils a little above that point ; so that, at common temperatures 
it is a gas. In the fluid state it is lighter than any other liquid, 
having a specific gravity of 0.627. The density of its vapor is 
nearly twice that of air. It is combustible, giving a bright light, 
and much smoke ; and the vapor explodes with oxygen, produc- 
ing carbonic acid and water. Chlorine gas combines with it pro- 
ducing an oily liquid, which in taste, odor, and volatility bear a 
strong resemblance to the hydrocarburet of chlorine, but differ- 
ent from that substance in not yielding a chloride of carbon. It 
is largely absorbed by sulphuric acid, and forms with it a com- 
pound, the nature of which is not fully understood. Like the 
other carburets of hydrogen, it may be analyzed by detonating 
its vapor with oxygen gas, or by passing it over red hot peroxide 
of copper. 

415. Naphtha appears on the shores of the Caspian Sea, and also in some 
parts of Italy. It is also separated from petroleum by distillation. A sub- 
stance which appears to be indentical with it, is obtained by distilling the 
tar formed in the process of manufacturing coal gas. It is a colorless liquid 
when pure ; but generally has a yellow tinge. It is very volatile, has a 
strong odor, and burns with a bright flame and much smoke. It dissolves 
in alcohol, ether, oils, and petroleum, but not in water. It is used to pre- 
serve potassium, sodium, &c. from contact with air. 

416. Naphthaline is also obtained from coal tar, by sublimation after the 
naphtha has been distilled off. It is a white crystaline solid, heavier than 
water, of a peculiar odor and pungent aromatic taste. In the open air it 
slowly evaporates like camphor. It scarcely dissolves in water, but does 
so in naphtha, in some of the oils, and especially in alcohol and ether. It 
does not burn readily, but when inflamed burns rapidly with much smoke. 
Acetic, oxalic and sulphuric acids dissolve naphthaline forming solutions 
which have some shade of red. The solution in sulphuric acid is a distinct 
acid called sulpho-naphthalic acid. This acid has some curious properties, 
but has not been applied to any use in the arts. Its salts are all soluble 
and combustible. 

417. Coal and Oil Gas. As organic substances consist of 
carbon, oxygen, hydrogen and sometimes nitrogen, among the 

414. Composition and properties of quadro-carburet of hydrogen. Its 
combination with chlorine. With sulphuric acid. How analyzed / 

415. Where is naphtha found ? Its properties and use. 

416. How is naphthaline obtained ? Properties. Its solutions in acids. 
Sulpho-naphthalic acid. 

417. Proportion of carburetted hydrogen in the products of destructive 
distillation. Bodies which afford large quantities of inflammable gas. 



CARBURETTED HYDROGEN. 165 

numerous products of their destructive distillation, a portion of 
carburetted hydrogen is usually found. The proportion which 
it bears to the other products will, other things being equal, de- 
pend upon the relative quantities of oxygen and hydrogen con- 
tained in the substance distilled ; large doses of oxygen leading 
to the formation of more carbonic acid and water. Resinous, 
bituminous and oleaginous substances are found to contain more 
hydrogen, relatively to the oxygen, than other bodies of organic 
origin ; and therefore afford, by destructive distillation, large 
quantities of inflammable gas. Hence the preference is due to 
this set of compounds, in the preparation of carburetted gases 
for illumination. Coal furnishes carburetted hydrogen by being 
distilled at a red heat, in large iron retorts ; but as the bitumen 
contained in the coal is the source of the gas, the different varie- 
ties of coal vary greatly in their fitness for this purpose. The 
best of all is the coal of Lancashire, England ; but the Richmond, 
Va. coal yields a large quantity of gas; while the anthracite, 
such as Lehigh, Lackawana, &c. affords little or none. Of dif- 
ferent specimens, that is best for producing carburetted hydro- 
gen, which contains the most bitumen and least sulphur. 

418. The combustion of a common lamp, or candle, is an ex- 
ample of the simultaneous production and consumption of oil 
gas. When flame is applied to the wick of a candle, the heat 
causes a portion of the wax or tallow to melt ; by means of ca- 
pillary attraction the melted portion rises in the wick, and is 
decomposed by the heat applied, which at the same time sets the 
resulting gas on fire. The combustion thus commenced, will 
continue so long as there is matter to feed it ; the heat of the 
flame constantly melting and decomposing fresh portions of the 
candle. In this operation, the wick is to be regarded only as a 
bundle of capillary tubes, serving to convey the fluid oil to the 
point where it is to be decomposed ; a glass capillary tube, will 
answer the same purpose. The wick being surrounded by in- 
flammable gas, and thus out of contact of the air, cannot burn, 
and contributes nothing to the flame. The gradual consumption 
of an ordinary cotton wick, is owing to the heat of the surround- 
ing flame, by which it undergoes destructive distillation ; and 
the crust of carbon which results, clogs the wick, in the case of 
a lamp, and prevents the free ascent of oil to supply the com- 
bustion. Part of this crust of carbon, or snuff as it is called, 
perhaps is derived from carburetted hydrogen which is decom- 

418. Oil gas generated and consumed in a common lamp. Why a candle 
burns brighter for being snuffed, or a lamp for being trimmed. Why a can- 
dle recently extinguished may be re-lighted without the actual contact of 
flame. 



166 CYANOGEN. 

posed by the heat in the interior of the flame. As soon as the 
exposed part of the wick of a candle becomes long enough to 
project beyond the flame into the air, it undergoes combustion 
and disappears. A very simple experiment will show the re- 
solution of oil into inflammable gas by heat. Let a common 
tallow candle, with a thick wick, burn until the uncovered part 
of the wick is nearly an inch in length, and then extinguish it 
suddenly. So long as the wick continues red hot, a stream of 
smoke will ascend from it. This column of smoke, contains 
carburetted hydrogen gas, produced from the tallow which the 
red hot wick continues to decompose ; and if a piece of burning 
paper be applied to it at the distance of two or three inches 
above the wick, it will take fire, and the flame running down, 
will re-light the candle. 

419. Bi-chloride of carbon discovered by M. Julin, consists of soft and 
white fibres, of an odor resembling spermaceti ; it burns with a red flame. 
Proto-chloride of carbon is a limpid, colorless liquid. Chloride of carbon, called 
the new chloride of Liebig, is a limpid, colorless liquid. Per -chloride of car- 
bon, of Faraday, is a transparent solid, of an aromatic odor. Chluro-carbonic 
acid, affords a singular instance where two acidifying principles unite with 
one base to form an acid. It was discovered by Dr. John Davy who called 
it phosgene gas. It is formed by exposing equal volumes of chlorino and 
carbonic oxide to the solar rays, when rapid combustion takes place, and 
they contract to one half their volume. Chloral a compound of carbon, oxy- 
gen and chlorine was discovered by Liebig by the mutual action of alcohol and 
chlorine. It is an oily transparent liquid. Periodide and the protiodide of 
carbon, have been obtained. Bromide of carbon is formed by means of the 
periodide of carbon and bromine. 



CHAPTER XVIII. 

COMPOUND OF CARBON AND NITROGEN.^ 

CYANOGEN. 

420. Bi-carburet of nitrogen or cyanogen. 1 nit. 14 to 2 carbon 12=26. 
This compound in many respects seems to act the part of a simple element. 
It was discovered by Gay Lussac. It is obtained by the action of heat on 
cyauuret of mercury contained in a retort. It is conducted over mercury. 
The cyanuret, (formerly prussiate,) of mercury is simply resolved by heat 
into cyanogen gas and mercury, its components. The vapor of mercury is 
condensed in the pneumatic trough, and the gas passes over. 

This gas is colorless, has a pungent odor, is condensible into 

419. Compounds of carbon with chlorine, iodine and bromine. 

420. Composition and discovery of cyanogen. How obtained? Properties, 
product of its combustion. Its solutions. ' 



CYANOGEN AND OXYGEN. 167 

a liquid by a pressure of 3| atmospheres; its sp. gr. is 1.8. 
It extinguishes burning bodies, but burns when set on fire in 
the air, producing carbonic acid, and liberating nitrogen gas ; 
it may also be exploded when mixed with oxygen gas. It is 
very soluble in water, and still more so in alcohol ; and its 
solutions have acid properties ; these, however, do not belong 
to cyanogen, but are due to acids which are generated by the 
reaction of the elements. 

421. Cyanogen, though a compound body, is strongly analo- 
gous to the simple electro-negatives : tending to combine with 
metals and other electro-positive simple bodies, and forming with 
them compounds which resemble the chlorides, iodies, &c. ; 
these compounds are called cyanurets or cyanides. It also forms 
acids by uniting with oxygen and hydrogen, respectively. 

The name cyanogen, (from the Greek kuanos, blue, added to 
gennao,) implies generator of blue color ; and was given it by its 
discoverer Gay Lussac^ from its being contained in Prussian 
blue, to the composition of which it is essential. The latter 
substance will be considered in treating of iron, which is its 
base. 

Compounds of Cyanogen and Oxygen. 

422. Cyanous Acid. There are two isomeric compounds, or consisting of 
the same proportions of cyanogen and oxygen, viz. one equivalent of each ; 
yet notwithstanding this indentity of composition, their properties are en- 
tirely distinct.* One of them, called cyanous acid of Liebig, forms salts 
possessing the property of detonating by friction or percussion; and is fre- 
quently called fulminic acid. One of its salts is called fulminate of mercury. 
This compound, now much used for priming fire arms, under the name of 
percussion powder, is formed by dissolving mercury in nitric acid, and, after 
the solution has become cool, adding alcohol. In the violent action which 
ensues, nitrous and ethereal fumes are given oft', and a white precipitate 
subsides, which is the fulminating murcury. By substituting silver for mer- 
cury, a fulminate of silver may be obtained, which explodes rather more 
readily than that of mercury. 

423. Cyanous Acid of Wohler is formed when cyanogen gas is passed into 
a hot aqueous solution of an alkali, where water is decomposed and the cya- 
nite and hydro-cyanate of the alkali are formed, as the chlorate and hydro- 
chlorate are, in similar circumstances. The cyanite of potassa is best ob- 
tained by applying a low red heat to a mixture of equal parts of ferro-cyan- 
ate,(triple prussiate,) of potassa and peroxide of manganese. The cyanogen 
of the ferrocyanic acid takes oxygen from the oxide of manganese, and the 

* See Isomerism, note to § 402. 

421. Resemblance to simple electro-negatives. Origin of the name. 

422. Two compounds of cyanogen and oxygen. Cyanous acid of Liebig. 
Fulminates. 

423. Cyanous acid of Wohler. Anhydrous cyanous acid. 



168 CYANOGEN AND HYDROGEN. 

cyanous acid, so formed, unites with the potassa. The cyanite of potassa 
is then dissolved by boiling alcohol, and deposits as the solution cools. By 
dissolving this salt in cold water, and adding it to a solution of nitrate of 
silver, a cyanite of silver is precipitated ; which, may be decomposed by a 
current of sulphuretted hydrogen gas. The sulphuret of silver is precipita- 
ted, and the cyanous acid remains in solution. It is decomposed in a few 
hours, being acted on by the water so as to form carbonate of ammonia. 
The same resolution of cyanous acid and ammonia is effected by boiling the 
cyanite of potassa in water, when carbonate of potassa remains and ammo- 
nia escapes ; and if a dilute acid stronger than the cyanic be added to solu- 
tion of cyanite of potassa, carbonic acid escapes, while the stronger acid 
forms salts with the potassa and ammonia. If an undiluted acid be used, 
the cyanous acid remains undecomposed a short time, and gives an odor 
like vinegar. 

Anhydrous cyanous acid was obtained by M. Wohler, by distilling anhy- 
drous cyanic acid, and collecting the products in cool vessels. Cyanous 
acid thus obtained is a colorless liquid, very volatile, which forms a soluble 
salt with baryta, and an insoluble one with oxide of silver and some other 
metallic oxides ; the latter being totally soluble in nitric acid. 

424. Cyanic Acid, consists of 1 Cyan. 26 added to 2 ox. 16=42. 

This compound is formed by boiling bichloride of cyanogen with water. 
Water is decomposed, its hydrogen combining with the chlorine and its 
oxygen with the cyanogen. By the evaporation most of the hydro-chloric 
acid is expelled, and on cooling the cyanic acid crystalizes. The crystals 
are colorless and at first, transparent ; but they become opake if exposed 
to air, and give off' water by gentle heat. This acid is nearly tasteless and 
volatile ; but if subjected to strong heat a portion of it is resolved into pure 
cyanous acid and oxygen. It is decomposed by potassium forming with its 
oxygen, both potassa and cyanuret of potassium. 

Compounds of Cyanogen and Hydrogen, 

425. Hydro-cyanic or Prussic Acid, consists of 1 Cyan. 26 
added to 1 Hyd. 1=27. This acid by its combination with the 
oxide of iron produces Prussian blue. It was discovered by 
Scheele in 1780, but he only obtained it in solution with a large 
proportion of water. Gay Lussac first obtained it pure. It has 
never been found uncombined in nature ; though it is said to 
exist in the leaves, flowers, and kernels of the peach, and al- 
mond, and in the bark of certain plants. Thenard however, 
speaks doubtfully of the existence of this acid in those vegetable 
substances. Most writers are silent on the subject \ but Profes- 
sor Silliman says, that if peach, laurel, or almond water be 
combined with lime or an alkali, it will preciptate Prussian blue 
from a solution of iron. It is produced during many chemical 
operations ; it results in some degree whenever any substance 

424. Composition of cyanic acid. How formed. Its crystals. Solubility 
in water and acids. Properties. Decomposition. 

425. Compounds formed by hydro-cyanic acid with oxide of iron. Dis- 
covery of this acid. Where found. How produced. 



CYANOGEN AND HYDROGEN 169 

vegetable or animal which contains nitrogen is distilled and from 
the action of nitric acid on vegetable and animal substances, and 
of ammoniacal gas upon burning charcoal. 

426. Hydro-cyanic acid is liquid, colorless, and corrosive. 
Its odor is strong, resembling that of peach blossoms. It red- 
dens litmus feebly. It is very volatile ; boils at 79° F. and 
freezes at zero. The voltaic pile decomposes it, the hydrogen 
going to the negative, and the cyanogen to the positive pole. Its 
vapor is inflammable and detonates with oxygen gas. This 
acid consists of 1 volume of vapor of carbon, | a volume of hy- 
drogen, and ^ a volume of nitrogen condensed into one volume. 
Its action on the animal system is very destructive, as has been 
proved by the experiments of Orfila, Magendie and others. The 
end of a small tube having been touched to a drop of this acid 
was put into the mouth of a dog ; the animal made two or three 
rapid inspirations and fell dead. One drop of the acid was ap- 
plied to the eye of a dog, and the effects were scarcely less 
sudden than in the other case. Prussic acid, says Thenard, is 
without doubt, the most active and mortal of all known poisons, 
and a knowledge of its effects, renders less extraordinary those 
sudden deaths by poison so common in the annals of Italy. It 
acts upon the system by destroying the sensibility and the power 
of voluntary contraction of the muscles. 

427. When introduced with some iron under a bell glass with mercury, 
and adding water to the mixture, it gradually disengages hydrogen gas, and 
Prussian blue is produced. The production of this color furnishes a method 
of detecting the poison when used criminally. Portions of the stomach of 
a person supposed to be destroyed by prussic acid, are cut up and introduc- 
ed into a retort with water slightly impregnated with sulphuric acid. If, 
on testing them with a prepared solution of the protoxide of iron, prussian 
blue is formed, there must have been present, hydro-cyanic acid. The sul- 
phate of copper, furnishes a still more satisfactory test. 

Hydro-cyanic or prussic acid unites with most alkaline bases, 
forming salts which are called prussiates or hydro-cyanites. These 
salts are poisonous. Prussic acid is used as a medical agent with 
some success but it is of too dangerous a nature, to be employed 
without great caution.* 

* The melancholy and mysterious end of the admired poetess L. E. Lan- 
don, afterwards Mrs. McLean, who was discovered dead with a phial of 
this poison in her hand, was the subject of much remark a few years since. 
In one of her novels, she made a prominent character terminate a wretched 
existence by using a liquid which she had prepared from " almond blossoms," 
to be kept ready for use in case of emergency. Who can estimate or con- 
trol the power of a morbid imagination ? 

426. Properties of hydro-cyanic acid. Decomposition by the voltaic pile, 
&c. Action on the animal system. 

427. Tests of the presence of hydro-cyanic acid. Union with alkaline 
bases. Use in medicine. 

15 



170 BORON. 

428. Chloride of Cyanogen, sometimes called cyanuret of chlorine, and 
cyanide of chlorine, was discovered by Berthollet ; he named it oxyprussic 
acid, on the supposition that it was composed of prussic acid and oxygen. 
Gay Lussac, who afterwards studied its nature, called it chlorocyanic acid. 

It was not obtained in purity, until about the year 1827, when it was 
procured by exposing powdered cyanuret, (prussiate of mercury)moistened 
with water, to the action of chlorine gas contained in a closely stopped 
bottle. After a few hours, the color of the chlorine disappeared, the cya- 
nuret of mercury was converted into the solid bi-ehloride of mercury, (cor- 
rosive sublimate,) and a gaseous chloride of cyanogen filled the bottle. 
This acid is a limpid, colorless liquid at 10° ; and above this, at the com- 
mon pressure, it is a gas. When enclosed in sealed tubes, it is liquid at 
68° Fahrenheit, being then under the pressure of 4 atmospheres created 
by its own vapor. It is poisonous to the animal system ; the vapor is of- 
fensive and injurious to the eyes ; its taste is caustic. It is very soluble 
in water, and alcohol; it is absorbed by alkalies, and if an acid be then 
added, an effervescence takes place, carbonic acid is evolved, and ammonia, 
hydrochloric acid, and probably hydrocyanic acid are formed. It precipi- 
tates green, the solutions of the protoxide of iron ; this precipitate becomes 
a beautiful blue by the addition of sulphuric acid, or sulphate of iron ; but 
if potassa be mixed with the chloride of cyanogen before adding the salt of 
iron, this precipitate is not formed. 

429. Perchloride (or bichloride) of Cyanogen. We have, in this compound, 
twice as much chlorine, as in the chloride of cyanogen; that is, 2 atoms of 
chlorine to 1 of cyanogen. It was discovered by M. Serullas, and is pre- 
pared by adding anhydrous prussic acid, to dry chlorine. It is solid at com- 
mon temperatures. Its vapor is acrid and poisonous. It is rapidly decom- 
posed by hot water, forming hydrochloric and cyanic acids. 

430. Bromide of Cyanogen resembles prussic acid in its noxious quali- 
ties. On account of the danger, attending its preparation, and the difficul- 
ty of obtaining a sufficient supply of bromine, it has hitherto been little 
studied. 

Iodide of Cyanogen is obtained by heating a mixture of 1 part of iodine, 
and 2 of the cyanuret of mercury. The violet vapors of iodines which first 
appear, are succeeded by white fumes, arising from the decomposition of 
the cyanuret ; these, when condensed in a receiver, settle upon its sides re- 
sembling flocks of cotton. The iodide of cyanogen is composed of 1 equiv- 
alent of cyanogen, 26, with 1 of iodine 124, its chemical equiv. is, there- 
fore, 150. 

431. Boron. Equiv. 8. The discovery of this simple element is, 
by English Chemists, ascribed to Sir Humphrey Davy, who, in 
1807 obtained it by exposing boracic acid to the action of 500 
pairs of galvanic plates. The French Chemists assert that it 
was discovered in 1809 by Gay Lussac and Thenard. It ap- 
pears that, though Davy discovered the existence of such an 
element, he did not obtain it in sufficient quantity to determine 
its properties. 

428. Synonymes of chloride of cyanogen. How first obtained pure. 
Properties. Its precipitates with protoxide of iron. 

429. Composition of the perchloride of cyanogen. Discovery, prepara- 
tion and properties. 

430. Bromide of cyanogen. Iodide of cyanogen. 

431. Discovery of boron. Manner in which it was obtained by Davy. 
By Gay Lussac and Thenard. 



BORON AND OXYGEN. 



171 



Thenard says, " According to Davy, when boracic acid is brought in 
contact with the two poles of a very powerful battery, there appears at the 
negative poie, a small brown spot, which he attributes to the presence of 
boron, while the oxygen of the acid appears at the positive pole. But it is 
not possible, by this means to obtain an appreciable quantity of boron."* 
It was obtained by Gay Lussac, and Thenard, by heating equal parts of 
boracic acid, and potassium, in a porcelain or copper tube hermetically 
sealed at one end. The tube is heated to redness, one part of the acid is 
decomposed, giving off oxygen to the potassium; a portion of the acid not 
decomposed, combines with the newly formed oxide of potassium ; and the 
result of the operation, is the sub-borate of potassa, and boron. This salt 
is then dissolved into water, and the boron precipitated.f Berzelius re- 
commends as the easiest and most economical mode of preparing it, to de- 
compose the fluo- 
borate of potassa, 
by heating with po- 
tassium. 

432. By Dr. Hare's 
method boracic acid 
is put with the po- 
tassium into a cop- 
per cup (Fig. 88.) 
supported by a cy- 
linder of copper C ; 
— A A are rods 
which support a 
large receiver. One 
of th e pipes, P, com- 
municates with an 
air pump. The 
air being exhausted 
from the receiver, 
an iron rod heated 
to redness, is intro- 
duced through the 
cylinder B, until it 
touches the bottom 
of the cup. The cup 
is soon heated and a 
deep red flame ap- 
pears to cover the 
whole mass. On 
cooling, it is found 
that the potassium 
has taken from the 
acid its oxygen, 
forming the oxide of 
potassium,(potash,) 
while pure boron 
remains. 




* Thenard Traite de Chimie, Tome I. p. 212. 
t Traite de Chimie, Tome II. p. 137. 



432. Dr. Hare's method of obtaining boron from boracic acid. 



172 BORACIC ACID. 

433. Boron appears at ordinary temperatures, as an olive green 
powder. It is insipid to the taste, inodorous, and insoluble, not 
only in water, but in ether, alcohol, or oils. It is a non-con- 
ductor of electricity j absorbs oxygen at a high temperature, 
giving off light, and it burns spontaneously in chlorine gas. It 
decomposes nitric acid, taking a portion of its oxygen, and thus 
forming boracic acid, while nitric oxide is liberated. 

Compounds of Boron and Oxygen. 

434. Boracic Acid. 1 bor. 8 + 2 ox. 16=24. It is the only 
known compound of boron and oxygen. It was first obtained 
from Borax, or the sub-boratc of soda, a native alkaline salt. 

Boracic acid was discovered by Homberg, a Chemist of the 
Academy of Sciences of Paris in 1702. It was for many years 
known by the name of Homherg's sedative salt, and was obtained 
from the borate of soda by means of acids, which, uniting with 
the soda, liberated the boracic acid. Until its decomposition by 
Davy, and the French Chemists about 1808, it was regarded as 
a simple body. It was then found to be composed of oxygen and 
a very combustible substance which was named boron ; the lat- 
ter, as it cannot, by any known methods, be decomposed, is now 
ranked among the simple elements. 

435. Natural History. Boracic acid is found in solution, in 
the hot springs of Lipari, in many of the small lakes of Tuscany, 
and in concretions upon their borders. It exists extensively in 
lakes in the East Indies, though usually in combination with 
soda, forming borax. It is found in the craters of volcanos, and 
is a constituent of boracic tourmaline, and some other minerals. 
So common has this acid become in commerce, that it is some- 
times used with soda in the manufacture of borax. 

For chemical experiments, and medicinal purposes, boracic acid is usually 
obtained from the decomposition of borax, or the borate of soda by sulphuric 
acid, and boiling water, sulphate of soda is formed, and boracic acid is lib- 
erated ; the latter, on evaporating and cooling the solution, is precipitated 
in shining, seal}- crystals. The acid being now combined with some water ; 
is a hydrate ; but, by exposure to a strong red heat, it melts into a trans- 
parent glassy substance. 

Vitrified boracic acid should be preserved in well stopped bottles, other- 
wise it absorbs water from the air, and loses its transparency. In the state 
of a hydrate, its specific gravity is 1.48, in the purified or vitreous state, it 

433. Properties of boron, &c. 

434. Composition of boracic acid. From what first obtained ? Discovery. 
Synonymes, &c. How obtained from the borate of soda ? When discovered 
to be compound ? 

435. Natural history. How obtained for chemical experiments and me- 
dicinal purposes ? Properties. Crystals of boracic acid. 



CHLORIDE OF BORON. 173 

is 1.80. It is inodorous, and has a bitter, rather than an acid taste. It 
effervesces with the alkaline carbonates, though when applied to turmeric 
paper, it acts like an alkali, giving it a brown color ; it reddens vegetable 
colors. In solution with alcohol, it barns with a beautiful pale green 
flame. 

The form of crystals of boracic acid are hexahedral, they have a pearly 
whiteness, and feel smooth and oily like spermaceti. They contain, 
Boracic acid 24, or one equivalent. 
Water 18, " do. 

Equiv. of boracic acid 42. 
436. Boracic acid, like hydrochloric and hydrofluoric acids, was long 
ranked among undecomposed bodies ; but like them, it is now found, both 
by analysis and synthesis, to consist of an inflammable basis, uniting to a 
supporter of combustion ; but while the base of boron combines with oxy- 
gen to form boracic acid, we have found the hydro-chloric acid having in- 
flammable hydrogen for its base united to a supporter of combustion, chlo- 
rine. The hydrofluoric may still be regarded as of a doubtful nature, though 
at present, it is usually ranked among the hydracids. 

437. Chloride of Boron is formed by the combustion of boron 
in chlorine gas. As one equivalent of boron 8, unites with 2 
equivalents of chlorine, 72, the representative number of this 
chloride is 30 ; and it is usually called, on account of its com- 
position the bi-chloride of boron. 

Sir Humphrey Davy first observed, that boron takes fire spontaneously 
in an atmosphere of chlorine, and burns with a vivid light. Berzelius af- 
terwards commenced a series of experiments, to ascertain the nature of the 
compound formed by this combustion. He found it to be a gas which is 
rapidly absorbed by water, when double decomposition takes place, and 
hydro-chloric and boracic acids are produced. M. Dumas and M. Despretz 
have found that the bi-chloride of boron may be generated by the action of 
dry chlorine on a mixture of boracic acid and charcoal, heated to redness in 
a porcelain tube. 

438. Fluoride of boron is generally known among Chemists, by the name 
ofjiuoboric acid gas ; but its nature and composition, remain doubtful. If 
fluorine could be obtained in an uncombined state, and then united with the 
inflammable boron, the result would be an undoubted fluoride of boron ; 
but, as fluoric acid has not yet been decomposed, its combinations are still 
regarded as of an uncertain character. " The chief difficulty in determining 
the nature of hydro-fluoric acid," says Turner, " arises from the water of 
the sulphuric acid which is employed in its preparation. To avoid this 
source of uncertainty, Gay Lussac and Thenard made a mixture of vitrified 
boracic acid, and fluor spar, and exposed it, in a leaden retort, to heat, 
under the expectation that as no water was present, anhydrous fluoric acid 
would be obtained. In this, however, they were disappointed; but a new 
gas came over, to which they applied the term of fluo-boric gas." The gas 
may be formed by the action of hydro-fluoric acid on a solution of boracic 
acid. Some suppose, that in the decomposition of fluor spar, (fluoride of 



436. Acids which were formerly ranked among undecomposed bodies. 

437. Chloride of boron. ,- 

438. Fluoride cf boron. Synonyme. Its doubtful nature. Experiment 
of Gay Lussac and Thenard. Explanations. Fluo-borates. Properties of 
fluoride of boron. 

15* 



174 SILICON. 

calcium,) the two substances interchange elements, the calcium and oxygen 
uniting to form lime, and a portion of free boracic acid forming with the 
lime, while borate of lime, boron, and fluorine, enter into a direct combina- 
tion. The discoverers of this gas regarded it as a compound of fluoric and 
boracic acids, and therefore named it fluo-boracic acid, and the salts which 
it forms with alkalies, fluoborates. 

While fluoric acid has a powerful action upon glass, the fluo-boric acid, 
(or fluoride of boron,) has no effect upon it, its affinity for silex being neu- 
tralized by the presence of boron. It carbonizes animal and vegetable sub- 
stances, extinguishes flame, and is irrespirable. When absorbed by water, 
for which it has great affinity, it forms a dense, fuming, and corrosive liquid, 
somewhat resembling sulphuric acid, equally powerful in its effects on ve- 
getable blues. 



CHAPTER XIX. 

SILICON. PHOSPHORUS. 

439. Silicon, Equiv. 8. We should, reasoning a priori, ex- 
pect that the simple, or undecomposible elements might be more 
easily understood than compounds ; but this is not generally 
the case. Indeed, most of these elements, except some of the 
metals, are found in nature only in combination, from which, 
science alone has taught us how to disengage them. Thus, 
though silicon, in combination with oxygen, forms silex, one of 
the most abundant substances in nature, it has remained hidden 
from our observation, till within a few years j and it is only by 
difficult and complicated processes, that it has been obtained in 
quantities sufficient to render observations and experiments upon 
it, of a definite and satisfactory nature. 

440. Sir Humphrey Davy by experiments with silex, or sili- 
ceous earth and heated potassium, discovered that the former is 
a compound of oxygen and a peculiar base, to which, on the 
supposition of its being a metal, he gave the name of silicium, 
corresponding to calcium and potassium, the metallic bases of 
lime and potash. This substance has continued to be classed 
among the metals, until Berzelius has proved that it is infusible, 
devoid of metallic lustre, a non-conductor of electricity, and in 
short is destitute of all the distinguishing characteristics of 
metals. On account of its resemblance to boron and carbon in 
being combustible, it is by late Chemists, ranked among the 

439. Why simple bodies are less readily understood than compound. Ob- 
scure nature of silicon. 

440, Discovery of the compound nature of silex. Change of the name 
silicium to silicon. 



SILICON AND OXYGEN. 



175 



non- metallic combustibles, and in corresponding terminology 
called silicon. 

441. Berzelius states,* that pure silicon is of a dark brown 
color, exhibiting no metallic lustre even by rubbing, and like 
earthy bodies, opposes resistance to the body against which it 
is rubbed. It leaves a stain upon glass vessels, adhering 
strongly to them when dry. It is destitute of taste or odor, and 
has no action upon vegetable colors. It is a bad conductor of 
heat and electricity, burns neither in the air nor in oxygen, and 
remains unaffected by the flame of the blowpipe. It decomposes 
water, and becomes converted into silex by its union with ox- 
ygen. 

442. Silicon was first ob- 
tained pure by Berzelius in 
1824, by the action of potas- 
sium on fluo-silicic acid gas. 
Dr. Hare has invented a con- 
venient apparatus for this pur- 
pose. A bell glass (Fig. 89.) 
is so fixed that it may be con- 
nected with an air pump ; a 
platinum wire is suspended 
within the bell glass, and a cup 
containing potassium hangs 
just below the wire. The air 
being exhausted from the bell 
glass, fluosilicic acid, (or fluo- 
ride of silicon,) is admitted, 
and the platinum wire ignited 
by an electric spark. The po- 
tassium is inflamed, and in 
burning, decomposes the fluo- 
silicic acid, giving rise to a 
peculiar deep red flame, 
and chocolate colored fumes, 
which condense into flakes 
forming, (except in color,) aj 
miniature representation of af 
snow storm. On washing the 
precipitate which is collected after this combustion, pure silicon, which is 
insoluble, is obtained, the residue being chiefly fluoride of potassium. 

Compound of Silicon and Oxygen, 

443. Silicic acid. 1 silicon 8+1 o/ oxy. 8=16. It was cal- 

* See Memoire de Berzelius, finals de Chimie, Tome xxvii. p. 341. Those 
who have not access to the original memoir may find an abridged transla- 
tion in the author's Dictionary of Chemistry, pp. 414 — 416. 

441. Properties of silicon. 

442. Dr. Hare's method of obtaining silicon from fluo-silicic acid. 




176 SILICON. , 

led silicic acid, from its analogy with boracic and fluoric acids, 
and because, like acids, it saturates the alkalies. It is often 
called silex ; in the laboratory silica. It has long been known 
in the arts, and was called by ancient Chemists, verifiable earth, 
because it entered into the composition of glass. It is extremely 
diffused in nature, being the principal constituent of most min- 
eral substances. It is found nearly pure in flint, white sand, 
quartz crystals, calcedony, and various other minerals. 

444. It may be prepared by heating to a red heat flint, or 
quartz crystals, and throwing them into water. 

445. Physical and Chemical properties. Silica is a light, white 
powder, insipid, tasteless, and harsh to the touch. It has no 
effect on vegetable colors, is not caustic, and has no alkaline 
properties, except its affinity for fluoric acid, which acts power- 
fully upon it. It combines with fixed alkalies and metallic ox- 
ides, and is therefore termed silicic acid, and its compounds with 
alkaline bases, silicates. 

When dry, silica neither dissolves in water nor is absorbed by it, but in 
its nascent state, or when just precipitated, it dissolves freely in this liquid. 
It is a remarkable fact, that silica, on evaporation, should thus lose its pro- 
perty of dissolving with water ; and this otters an explanation of the vast 
collection of silicious crystals which nature presents in cavilies of quartz, 
agale, and many other minerals of the same class; and which may be re- 
garded as hydrates of silica , in which the water of crystalization exceeds in 
volume the mass of silica. In some hot springs as the geysers of Iceland, 
silica is found in solution, whieh is promoted by the soda contained in their 
waters. 

446. When silica is fused with a large portion of potassa, a 
vitreous mass is produced which is soluble in water. This was 
known by the old writers under the name of liquor of flints. If 
the proportion of silica and alkali be reversed, (that is, a small 
portion of alkali added to silica,) and the mixture be fused, the 
result is a transparent, brittle compound which is insoluble in 
water, and is attacked by no acid except the hydro-fluoric ; 
this compound is glass. " Every kind of glass is a silicate, or a 
compound of silica and an alkali, and all its varieties are owing 
to differences in the proportions of the constituents, to the nature 
of the alkali, or the presence of foreign matter. Thus, green 
bottle glass is made of impure materials, such as river sand, 
which contains iron, and the most common kind of kelp or 
pearlashes. Crown glass for windows is made of purer alkali 



443. Composition of silicic acid. Its synonymes. Its existence in na- 
ture. 

444. Mode of obtaining it. 

445. Properties. Silicates. Its action with water. Crystals. 

446. Liquor of flints. Glass. Cause of varieties of glass. 



COMPOUNDS. 177 

and sand which is free from iron. Plate glass for looking- glass- 
es is composed of sand and alkali in their purest state, and in 
the formation of flint glass besides these pure ingredients, a 
quantity of red lead or litharge is employed."* Black oxide 
of manganese improves the transparency of glass, by oxidizing 
any carbonaceous substances in the materials used ; and boracic 
acid or borax are employed in making imitations of gems. 
Silica is also used in the composition of porcelain ; as pure clay 
without any silicious earth would shrink too much for this 
purpose. 

Compounds of Silica with Chlorine, Sulphur and Fluorine. 

447. Chloride of Silicon is formed by the combustion of silicon in chlorine 
gas. It is liquid, limpid, and volatile, evaporating in opeu vessels, in the 
form of a white vapor. Its odor resembles that of cyanogen. Water 
changes it into muriatic acid and silica. 

448. Sulphuret of Silicon. Silicon when heated with the vapor of sulphur, 
unites with it, forming a white earthy looking substance. Water converts 
it into sulphuretted hydrogen and silica. The former escapes with efferves- 
cense, the latter dissolves. 

449. Fluoride of Silicium, or Fluo-silicic Acid, Gas is composed of 1 Silicon 
8 added to Fluor 10=18. 

In treating of hydro-fluoric acid, especially its action upon glass we found 
that in decomposing that substance a peculiar gas was generated. This is 
the fluo-silicic acid. It is a colorless gas, of a strong odor and caustic taste. 
It extinguishes combustion, is irritating to the lungs, and is not decomposed 
by heat. Its specific gravity is 3.57. Water acts upon it, precipitating 
silica in a gelatinous state. It forms white fumes with the atmosphere by 
combining with aqueous vapor. When distilled in a receiver containing 
water, it becomes covered with a silicious crust which at length covers the 
water, and it is necessary to shake the vessel and break this crust that the 
condensation may not thus be prevented. Moist substances exposed to this 
gas, become encrusted with it, so as to resemble petrifactions ; thus insects, 
reptiles, and vegetable substances, by being moistened and placed in an at- 
mosphere of this gas may be made to appear like natural fossils. 

It may be prepared for experiments by heating in a retort three parts of 
fluor spar and two of silica, with an equal weight of sulphuric acid ; it must 
be collected over mercury. When dissolved in water, it becomes the 
silico-hydro fluoric or siiicated fluoric acid ; the hydrogen of the water com- 
bining with the fluorine, and the oxygen with the silicon. 

PHOSPHORUS. EQUIV. 12. 

450. Phosphorus combines so readily with oxygen and other 
* Turner. 



447. Formation and properties of chloride of silicon. 

448. Formation of sulphuret of silicon. 

449. Composition of fluo-silicic acid. When produced. Properties. 
Action with water. How prepared for experiments ? Change when dis- 
solved in water. 



178 PHOSPHORUS. 

substances that it is not found pure in nature. It is solid, but 
so soft and flexible that it may be bent with the fingers like wax. 
It may be cut with a knife. Its color when pure is white, but 
on exposure to air and moisture it assumes a brownish hue. 
When excluded from contact with the air, light gives it a red 
color. Its specific gravity is 1.77. Its odor is feeble, somewhat 
resembling that of hydrogen gas. It is always luminous in the 
dark, hence its name — the light-bearer, from the Greek phos, 
light, phero, to bear. 

451. History. Phosphorus was discovered in 1669, by Brandt, 
an alchemist of Hamburgh, in his search for the philosopher'' s 
stone, or the art of converting the common metals into gold and 
silver. The preparation of phosphorus, however, remained a 
secret until 1737, when a stranger in Paris, communicated it to 
a committee of the French Academy of sciences. But the meth- 
od then used was tedious and imperfect. In 1769, Gahn of 
Sweden, in connection with Scheele, published a newly discov- 
ered process for obtaining phosphorus by distillation of bones. 
This is the one now generally followed. Phosphorus being thus 
easily obtained, chemists were able to study its properties. 
Much is due to the labors of M. Pelletier, who first combined 
it with sulphur and many of the metals ; to Lavoisier, who in- 
vestigated its combination with oxygen ; to Dulong and Davy, 
who studied its different acids, and to Berzelius, who has ex- 
amined the combinations of these acids, with different bases. 

452. The solid parts of the bones of animals consist, princi- 
pally, of the phosphate of lime, a salt formed by the union of 
phosphoric acid and lime. A man of common stature is said to 
have about one pound of phosphorus in his bones. Phosphoric 
acid is a compound of phosphorus and oxygen. From the de- 
composition of the phosphate of lime, in bones, phosphorus is 
obtained. 

The usual process is, to digest in sulphuric acid a quantity of calcined 
bones, (that is, bones burnt in an open fire,) reduced to powder. The phos- 
phate of lime is decomposed by the sulphuric acid, which, uniting with the 
lime forms sulphate of lime ; the disengaged phosphoric acid being now 
mixed with powdered charcoal, and strongly heated in an earthen retort, 
parts with its oxygen to the charcoal, forming carbonic acid, while phos- 
phorus passes over in the form of vapor, and may be collected by placing 
the beak of the retort under a receiver filled with water. When first ob- 
tained it is of a red color, owing to the presence of the phosphuret of car- 
bon, from which it may be purified, by another distillation. 



450. Why is phosphorus not found pure in nature ? Its physical proper- 
ties. Derivation of the name. 

451. History. 

452. Where does phosphorus exist ? Mode of obtaining it. 



PHOSPHORUS. 



179 



453. Phosphorus is highly inflammable, and gives off a gar- 
lic odor when burning. When exposed to the air at common 
temperatures it undergoes slow combustion, appearing in the 
light as a white smoke and in the dark as a beautiful blue lumi- 
nous cloud. It should be kept in water, as a slight degree of 
heat, in the open air readily kindles it to a flame. It melts at 
99° F. takes fire at 108<> ; and volatizes at 219°. 

454. Perhaps no substance affords such a variety of brilliant experiments, 
especially for an evening's exhibition, as phosphorus. 

Exp. 1st. Words or figures drawn on the wall of a dark and warm room 
with a stick of phosphorus will leave traces, which in the night will appear 
like fire. 

Exp. 2nd. A few grains of phosphorus in the bottom of a wine glass 
will burn with brilliancy, and a succession of detonations, by pouring on 
water and sulphuric acid. 

Exp. 3d. Oil, in which phosphorus has been dissolved, when rubbed on 
the face and hands, exhibits the appearance of a lambent flame, playing over 
the features, accompanied with luminous clouds and flashes. Unless the 
phosphorus is entirely dissolved, this may prove a dangerous experiment; 
severe burns have been thus caused. 

Fig. 90. Fig. 91. 





mmm 



Exp. 4th. The combustion of phosphorus in 
oxygen gas, (Fig. 90,) or even an enclosed por- 
tion of atmospheric air, is attended with a 
splendor too great for the eye to endure. Dur- 
ing combustion dense white vapors like flakes 
of snow will fill the jar. These vapors are 
phosphoric acid, consisting of phosphorus and, 
oxygen. 

Exp. 5th. Eudiometry may be performed by 
consuming the oxygen of the air with phosphorus . If a cylinder of phosphorus 
be supported upon a wire within a glass matrass (Fig. 91,) inverted in a jar 
of water, the included air is gradually absorbed. In order to determine the 
quantity of oxygen in the air, we have only to ascertain the ratio between 
the quantity absorbed, and the quantity included. 




453. Inflammable nature, &c. 

454. Experiments with phosphorus. 



180 PHOSPHORUS AND OXYGEN. 

455. Phosphorus does not, at the ordinary pressure, burn in 
oxygen gas at a temperature below 80° ; but if the pressure is 
diminished, it becomes luminous in the dark, and burns. Ni- 
trogen, by rarefying the oxygen of the atmosphere, acts like the 
diminution of pressure, and singularly favors the combustion. 
Phosphorus forms combinations with most other combusti- 
ble bodies. With oxygen it enters into the composition of 
many minerals, and forms a large portion of the animal frame. 
It is employed in the arts for the construction of phosphoric 
matches, and in Chemistry for the analysis of air and the prepar- 
ation of phosphoric acid. It is a violent poison, though it is some- 
times used in medicine in very small doses. 

Combinations of Phosphorus and Oxygen. 

456. There is an uncertainty with respect to the number of 
combinations of these two elements. Dr. Turner remarks that 
" under the term phosphoric acid, Chemists have hitherto in- 
cluded two distinct acids, phosphoric, and pyro-phosphoric, com- 
pounds which afford an instance of a fact of much importance 
to the atomic theory : viz. That two substances may consist 
of the same ingredients, in the same proportion, and yet differ 
essentially in their chemical properties." These are isomeric 
bodies.* 

457. There are three known acid combinations of phosphorus 
and oxygen, which contain different proportions of their constit- 
uent elements. 

1. Phosphoric acid, 1 Phos. 12+2 Cx. 16=28. 

2. Phosphorous acid, 1 Phos. 12-j-l Ox. 8=23. 

3. Hypo-phosphorous acid, 2 Phos. 24+1 Ox. 8=82. 

458. Phosphoric acid may be obtained by the combustion of phosphorus in 
oxygen, gas, (see 1T 454, exp. 4th.) It may also be obtained by burning 
phosphorus in an enclosed portion of atmospheric air, occasionally raising 
the receiver, in order to let in fresh supplies of air, until all the phosphorus 
is consumed. 1 grain of phosphorus requires about 15 cubic inches of com- 
mon air, and of course about 4 cubic inches of oxygen for its saturation. 

459. This acid is white, solid, inodorous, and soluble in water, 

* See IT 402. with the note. 

455. Circumstances under which phosphorus burns in oxygen gas, &c. 
Combinations of phosphorus. Uses. 

456. Dr. Turner's remark respecting phosphoric and pyro-phosphoric 
acids. 

457. Names and composition of acid compounds of phosphorus and oxy- 
gen. 

458. How may phosphoric acid be obtained ? 

459. Properties, &c. 



PHOSPHORUS. 



181 



dissolving with a hissing noise, and forming if concentrated, 
a dense, oily liquid. Though decided in respect to its sour 
taste, its action on vegetable blue colors, and its effect in neu- 
tralizing alkalies, it does not decompose animal matter, like 
nitric and sulphuric acids. 



Fig. 92. 




460. Phosphoric acid may be decomposed 
by heating with charcoal in a retort a, (Fig. 
92,) placed over a furnace, b, the beak of the 
retort being immersed in the basin of the 
water, c. The phosphoric acid loses oxygen, 
which, uniting with the vapor of carbon from 
the charcoal, forms carbonic acid gas : the 
phosphorus passes over, being volatilized 
when the retort is at a red heat, and appears 
in the basin, in the form of a reddish wax. 

461. Pyro-phosphoric acid. Mr. Clark of 
Glasgow remarked that common phosphoi-ic 
acid is, by heat, converted into a substance, 
which, though unchanged in its constituents 
or in their combining proportions, exhibits 
properties of an essentially different kind ; this 
new acid he called Pyro-phosphoric* acid. 

Phosphoric acid produces with the oxide of 
silver a yellow salt, and renders a solution of 
albumen turbid. Pyro-phosphoric acid produces with the same oxide a 
white salt, and does "not destroy the transparency of albumen. Pyro-phos- 
phoric is less energetic, it has less saturating power, and is separated from 
its combinations by phosphoric acid. And yet the only visible effect of heat 
on phosphoric acid is to expel water, which, we should infer, would render 
the acid more powerful, rather than diminish its energies. 

462. Phosphorous acid. It was ascertained by Lavoisier, that 
the slow and rapid combustion of phosphorus produced two dis- 
tinct acids, the phosphorous and the phosphoric. At a high tem- 
perature, phosphorus, whether burning in common air or in oxy- 
gen gas, unites with its highest proportion of oxygen (two equiv- 
alents=16,) and produces phosphoric acid ; at a common tem- 
perature it unites with but one equivalent of oxygen (=8) and 
forms phospho?*0W5 acid. 

463. Sir Humphrey Davy first obtained pure phosphorous acid, by sublim- 
ing phosphorus through the pcrchloride of mercury, (corrosive sublimate.) 
The corrosive sublimate is put into a glass tube, connected at one end with 
a small receiver, (which is to be kept cool,) and at the other with a small 
tube containing phosphorus ; as heat is applied to the phosphorus, it rises 
in vapor, comes in contact with the corrosive sublimate, which it decom- 
poses by combining with its chlorine, and passes into the receiver in the 

* From the Greek pur fire, added to phosphoric. 

460. Decomposition of phosphoric acid. 

461. Discovery of pyro-phosphoric acid. Difference in the properties of 
phosphoric and pyro-phosphoric acids. 

462. Different products of the sIoav and rapid combustion of phosphorus. 

463. Mode of procuring phosphorous acid. 

16 



182 PHOSPHORUS AMD CHLORINE. 

form of a limpid fluid, which is the chloride of phosphorus. This, on being 
mixed with water, decomposes it ; the chlorine unites with the hydrogen of 
the water, forming hydrochloric acid ; while the phosphorus attaches itself 
to the oxygen, producing phosphorous acid. The solution being next eva- 
porated to the consistence of syrup, hydrochloric acid is expelled, and the 
residue, which is a hydrate of phosphorous acid, becomes solid and crystaline 
in cooling. 

464. From its tendency to unite with an additional quantity 
of oxygen, phosphorous acid is a powerful deoxidizing agent, 
and precipitates mercury, silver, and gold from their saline 
combination in the metallic form. On exposure to the air, orin 
contact with the nitric acid, it absorbs oxygen, and is converted 
into phosphoric acid. Phosphorous acid combines with salifiable 
bases, forming salts called phosphites ; it is acid to the taste, 
and reddens vegetable blue colors. Its odor resembles that of 
garlic. 

465. Hypo-phosphoric acid. Is so named on the supposition that it con- 
tains a smaller proportion of oxygen than the phosphorous acid. It com- 
bines with salifiable bases forming neutral salts, called hypo-phosphites, which 
are all remarkably soluble in water. Silliman suggests that this acid may 
be a triple compound of oxygen, hydrogen, and phosphorous, or &hydracid, 
in which case its proper name would be /ii/dro-phosphoric acid.* 

466. Oxide of Phosphorus. Phosphorus is usually made into 
small sticks of a few inches in length. As it must be preserved 
in water, it is usually kept in vials of this liquid. After being 
for some time exposed to the action of water, it becomes encrust- 
ed with a whitish substance, which is called the white oxide of 
phosphorus. The red colored residue which appears after the 
combustion of phosphorus, is called the red oxide of phosphorus. 
Thenard considers these two oxides identical, except that the 
white oxide is in the hydrated state, 

Phosphorus and Chlorine. 

467. There are two definite compounds of phosphorus with 
chlorine. One discovered by Davy, called the perchloride, the 
other discovered by Gay Lussac and Thenard, and called proto- 
chloride. Their component parts and chemical equivalents are 
as follows. 

* Silliman's Elements, Vol. 1. p. 429. 



464. Properties, salts, &c. 

465. Hypo-phosphoric acid. Its salts. Silliman's suggestion respecting 
its composition. 

466. Formation of the white oxide of phosphorus. Red oxide. 

467. Discovery and composition of the proto-chloride and per-chloride ot 
phosphorus. 



PHOSPHORUS AND HYDROGEN. 183 

Protochloride of Phos. 1 Phos. 12+1 Chlo. 36-48. 
Perchloride of Phos. 1 Phos. 12+2 Chlo. 72=84. 

468. The Protochloride of phosphorus may be obtained by 
passing the vapor of phosphorus over perchloride of mercury, 
.(corrosive sublimate,) in a heated glass tube ; the perchloride of 
mercury yields one proportion of chlorine to the phosphorus and 
becomes calomel, or the protochloride of mercury. The phos- 
phorus has become a volatile transparent liquid, very caustic, 
and heavier than water. It decomposes rapidly in water in 
which case a solution of hydrochloric, and phosphorous acids is 
the result. Its vapor is combustible. 

469. The Perchloride of phosphorus, sometimes called the bi- 
chloride and deutochloride is formed when dry phosphorus is 
burned in chlorine gas. 

Fig- 93. (Figure 93) represents a tubulated glass 

bottle containing chlorine gas, into which 
some phosphorus being introduced, it burns 
spontaneously, throwing off brilliant jets oi 
fire, and giving a pale white light. The 
bladder fastened to the tubulure is to give 
space for the expansion of the gas by heat, 
which, as the bottle is air tight, might other- 
wise, cause it to break. The white, solid, 
pulverulent substance which collects on the 
inside of the bottle is the per-chloride of 
phosphorus. It crystalizes in transparent 
prisms ; is volatile at a heat less than 212° ; 
decomposes water rapidly, forming with its 
elements, hydro-chloric and phosphoric 
acids. Some chemists regard the chlorides 
of phosphorus as acids, to which they give 
the name of chloro-phosphorous for the proto- 
chloride, and chloro-phosphoric for the per- 
chloride. When the per-chloride of phosphorus is heated with about one 
seventh of phosphorus, it passes to the state of proto-chloride. 

470. Phosphorus with bromine and iodine forms compounds termed bromides 
and iodides of phosphorus, but they are little understood. 

Phosphorus and Hydrogen. 

471. There are two compounds of phosphorus and hydrogen, 
viz. 

Proto phosphuretted Hydrogen, and Per-phosphuretted Hydrogen 



468. Proto-chloride of phosphorus. 

469. Per-chloride. 

470. Bromides and iodides of phosphorus. 

471. Composition of two compounds of phosphorus and hydrogen. The 
terminations in ide, uret, &c. 




184 



PHOSPHORUS. 



As in the chemical nomenclature, binary* compounds of substances of the 
electro-negative class, which are not acid, are designated by the termination 
ide, as oxide, chloride, bromide, &c, so binary combinations of the electro-pos- 
itive class, which are not of a metallic nature, are distinguished by the ter- 
mination uret, as phosphuret, carburet, sulphuret, &c. When the compound 
is gaseous, the termination uretted is used, as carburetted hydrogen, sulphuret- 
ted hydrogen, &c. 

472. Proto-phosphuretted Hydrogen is sometimes called the bi- 
hydruret of phosphorus, and hydro-phosphoric gas. It was dis- 
covered by Sir Humphrey Davy in 1812. 

It may be obtained when the solid hydrated phosphorus acid is heated in 
a close vessel. It is a colorless gas, with a disagreeable odor. It does not 
take fire spontaneously in the atmosphere, as phosphuretted hydrogen does ; 
but when mixed with atmospheric air, or pure oxygen, it detonates violently 
with the electric spark, or when heated to 300° F., it inflames sponta- 
neously in chlorine gas. 

473. Per-phosphuretted Hydrogen, (called also the Hydruret of 
Phosphorus,) may be obtained by boiling phosphorus in a small 
retort (Fig. 94,) with a hot solution of potash, which should 
entirely fill the vessel, and the beak of the retort should be made 
to dip into a vessel filled with the same solution. The gas, as it 

Fig. 94. is extricated, grad- 

ually expels the li- 
quid from the 
neck, and inflames, 
when allowed to es- 
cape into the air ,• or 
it may be collected 
under a bell glass, 
also filled with the 
same alkaline solu- 
tion. One peculiar 
property of this gas 
is, that of spontane- 
ously inflaming on mixture with common air or oxygen gas. 
This combustion is accompanied with a beautiful appearance. 
After the explosion, circular, horizontal rings, or coronas, of 
dense white smoke rise in the air, which increase in diameter, 
and become fainter as they ascend, f it is decomposed by heat, 
electricity, and the vapor of sulphur. Lights may sometimes be 

* A binary compound is one which consists of no more than two elements. 

f Some care is necessary in conducting this experiment, that as small a 
portion of air as possible shall be included in the retort, since the first bub- 
bles of phosphuretted hydrogen gas that are formed, will take fire as soon 

472. Proto-phosphuretted hydrogen. Discovery. Mode of obtaining it 
and its properties. 

473. Per-phosphuretted hydrogen, &c. Cause of lights seen at night in 
certain situations, &c. 




SULPHUR. 185 

seen at night around burying grounds, and swamps where 
animal and vegetable substances are undergoing decomposition, 
" Travelling once," says Silliman, " through a deep valley, 
in a dark night, between Wallingford and Durham, Conn., I was 
surrounded by multitudes of pale, lambent lights ; these were 
every moment changing their position, and some of them were 
within reach of my whip ; they were yellowish, but not intense." 

Thus does science explain to us the mysterious " Jack o' the 
Lantern" and " Will o' the Wisp," as being mere exhalations of 
gases which, on rising into the atmosphere, spontaneously in 
flame. 

475. Phosphuret of Carbon. The combination of phosphorus with carbon 
was first effected by M. Proust, in 1799 ; it is a soft, yellowish powder, 
destitute of smell or taste. It slowly imbibes moisture from the air, and 
then has an acid taste. 



CHAPTER XX. 

SULPHUR. EQUIV. 16. 

476. Natural History. Sulphur is found, as a mineral, in 
various parts of the world, especially in the vicinity of volcanoes. 
It is obtained in large quantities from the craters of volcanoes. 
It is generally massive, sometimes in a state of powder, or 
crystalline form. Much of the sulphur of commerce, is obtained 
by applying heat in close vessels to the natural compounds of 
the metals and sulphur, especially to iron pyrites. The volcanic 
sulphur is probably the result of similar decompositions. 

Properties. Sulphur is a brittle solid, of a citron or greenish 
yellow color, inodorous, except when heated by friction on fire, 
and nearly tasteless. It is about twice as heavy as water. It 
is a very bad conductor of heat and electricity, and becomes 
negatively electrified when rubbed. 

477. Sulphur fuses at about 216° Fahrenheit ; it is liuid between 230° 
and 280° Fahrenheit, and when cast into moulds, forms the common roll 
sulphur, or brimstone. As the temperature rises, it thickens and becomes 
darker colored, till at between 425° and 480°, it is so tenacious that the 
vessel may be inverted without spilling it. At 428°, if poured into water, 
it becomes a plastic mass, and is used for taking impressions of medals, &c. 

as they come in contact with air in the retort, which will be in danger of 
being broken in the percussion. 

475. Phosphuret of carbon. 

476. Sulphur found in a natural state. Sulphur of commerce, how ob- 
tained ? Properties. 

477. Affected by heat. Flowers of sulphur. Crystalized sulphur. 

16* 



186 



SULPHUR. 



Above 480°, it liquefies again, but not so perfectly as at 248°. At 550°, or 
600°, it sublimes rapidly; indeed, a slow evaporation commences below the 
freezing point. The vapor condenses on cold surfaces in the form of a 
crystaline powder, called flowers of sulphur. Sulphur may be crystalized by 
fusing several pounds of it in a large crucible, and allowing it to cool slowly. 
When a crust has formed upon the upper surface, it is to be perforated in 
two places by a hot iron rod, and the sulphur which remains melted, is to 
be poured out. If a sufficient quantity of sulphur has been used and the 
cooling very slow, octahedral crystals of sulphur will be found lining the 
crucible ; otherwise the crystalization will be irregular and confused. 

478. Sulphur is soluble in alcohol, provided the two bodies be brought 
together in the state of vapor; from this solution, water throws down the 
sulphur as a white hydrate called " milk of sulphur." This is the only 
combination of sulphur with water, the former being quite insoluble in the 
latter. 

479. Sulphur takes fire on being heated above 300° in the 
open air ; it burns with a blue flame, and if the air be quite dry, 
produces sulphurous acid gas; if moisture be present, some 
sulphuric acid is formed also. In pure oxygen gas, the com- 
bination is far more rapid and brilliant ; but the product is sul- 
phurous acid in this case also. Sulphur has numerous and im- 
portant uses in medicine. Mixed with charcoal and salt-petre, 
it forms gun-powder, the explosive property of which is owing 
to the sudden change of solids into gases. It is used for fire 
matches, for copying medals, and furnishes beautiful crystals 
for ornamental purpose. With iron filings, it is used as a 
cement. 

Fi 2- 95 ' Ex. If a gun -barrel, (Fig. 95,) 

heated to a red heat, have a piece 
of sulphur placed in one end of it, 
the jet of ignited sulphurous vapor 
will burn iron wire, as if ignited 
in oxygen gas ; and the iron will 
fall in the form of fused globules ; 
these are the proto-sulphurets 
of iron. Hydrate of potassa expos- 
ed to the jet, fuses into a sulphuret 
of fine red color. Combined with oxygen in the form of sulphurous and sul- 
phuric acids, sulphur is used in the arts of bleaching and dyeing. 

480. Compounds of sulphur and oxygen. Of these there are 
four, all of them being acids. 




1. Hyposulphurous acid, 1 Sulp. 

2. Sulphurous acid, 1 Sulp. 

3. Hyposulphuric acid, 2 Sulp. 

4. Sulphuric acid, 1 Sulp. 



16 added to 1 ox. 
16 " 2 ox. 

32 " 5 ox. 

16 " 3 ox. 



8: 



,24. 
32. 

72. 
40. 



478. Sulphur with alcohol. Hydrate of sulphur. 

479. Product of the combustion of sulphur. Uses. Exp. 

480. Names and composition of the compounds of sulphur and oxygen. 



SULPHUROUS ACID GAS. 187 

481. Hyposulphurous acid. This acid is only known in combination with 
bases, forming salts called hyposulphites. On adding a stronger acid, to lib- 
erate the hyposulphurous acid, the latter is immediately resolved into sul- 
phurous acid and sulphur. The hyposulphites are of no use in the arts ; 
their most interesting property, is, that their solutions dissolve large quan- 
tities of chloride of silver, giving intensely sweet compounds. 

482. Sulphurous Acid Gas. This is always the principal 
product of the combustion of sulphur in air, or oxygen gas, and 
is the sole product when moisture is not present. But the best 
mode of obtaining this gas, is by depriving sulphuric acid of a 
portion of its oxygen. Most of the metals decompose sulphuric 
acid, becoming oxidized at its expense. 

Put 2 parts of mercury, and 3 of sulphuric acid, into a glass retort, and 
apply the heat of a lamp. The peroxide of mercury is formed, and unites 
with some of the undecomposed acid, forming persulphate of inercury, which 
remains in the retort ; while the sulphurous acid gas escapes with efferves- 
cence, and is to be collected over mercury in the receiver. 

484. Properties. Sulphurous acid gas is transparent and col- 
orless. Its specific gravity is 2.22, (double that of oxygen,) it is 
less elastic than any other gas ; being condensed into a liquid by 
intense cold, or by a pressure of one additional atmosphere. Its 
pungent and suffocating odor, distinguishes it from all other gases. 
When pure, it is irrespirable, causing a spasmodic contraction of 
the glottis. If inhaled with air, it excites coughing and is inj urious 
to the lungs ; it is fatal to animals confined in it. Thus some 
naturalists make use of it to destroy the lives of butterflies and 
insects which they wish to preserve in the cabinet. It is incom- 
bustible, and extinguishes burning bodies. It has a great affinity 
for water, which, will absorb 33 times its bulk. The solution 
thus formed, has the odor and other properties of the gas itself, 
and may be substituted for it in many operations. It must, 
however, be kept in closely stopped bottles ; for, on exposure to 
the air, it rapidly absorbs oxygen, and is converted into sulphuric 
acid. Its strong affinity for oxygen renders it a powerful deox- 
idizing agent. 

485. This gas and its solution in water, possess the property 
of bleaching, and are used for that purpose to some extent ; thus 
straw bonnets are bleached by thetfumes of burning sulphur j 
and a red rose, or dahlia held in the same fumes, or dipped in 
aqueous sulphurous acid, will become white, except where por- 
tions have been protected by folds in the leaves. But the bleach- 
ing is not permanent, the coloring principle being only combined 

481. Hyposulphurous acid. 

482. How is sulphurous acid gas obtained ? Reduction of sulphuric acid, 
to sulphurous acid, by heating it with mercury. 

484. Properties of sulphurous acid gas. Its affinity for water and oxygen. 

485. Bleaching property. Effect of cold or pressure upon this acid. De- 
composition. Compounds. 



188 SULPHURIC ACID. 

with sulphurous acid, — not destroyed. Consequently, the color 
returns, when, by exposure to the air, the gaseous acid has been 
dissipated, the stronger acids, also, will restore the color, and 
the alkalies, by neutralizing the sulphurous acid, produce the 
same effect. Sulphurous acid liquefied by cold or pressure, is 
exceedingly volatile, and, by its evaporation, produces cold 
enough to freeze mercury, and to liquefy some other gases. 
This gas is not decomposed by heat alone ; but is deprived of 
oxygen, by being brought in contact with hydrogen, and some 
other oxidable substances, at a red heat. It combines with the 
salifiable bases forming salts, called sulphites. 

486. Hyposulphuric Acid is formed when sulphurous acid is passed into 
water, in which peroxide of manganese is suspended. Theory. The latter 
parts with 1 equivalent of its oxygen which uniting with the sulphurous 
acid forms the hyposulphuric. 

This acid is of no use in the arts, nor in the laboratory. Its salts are 
generally soluble, even those of the bases with which sulphuric acid would 
form insoluble salts. 

487. Sulphuric Acid is commonly known as oil of vitriol, 
having been at first, obtained by the distillation of green vitriol. 
Several of the salts of this acid have obtained the name of vitriol, 
from their glassy appearance ; as green vitriol, which is a sul- 
phate of protoxide of copper ; white vitriol, sulphate of the oxide 
of zinc. 

488. Physical and chemical properties. Pure sulphuric acid 
is transparent and colorless and of an oily consistency ; its taste 
is intensely sour, and its specific gravity, when most concentra- 
ted 1.85. It is one of the strongest acids known, combining 
with all the salifiable bodies, and even taking them away from 
almost all other acids, by its superior affinity It oxidizes many 
of the metals, and then combines with the oxides ; in some cases 
theacid must be strong, the metal being oxidized at its expense, 
as in the preparation of sulphurous acid gas, in other cases, the 
acid must be dilute, the water furnishing oxygen to the metal, 
and hydrogen gas being evolved. 

It has a very great affinity for water, uniting with it in every 
proportion. This combination is attended with condensation, 
on which account great heat is evolved j the increase of temper- 
ature sometimes exceeds 212°. Snow is melted by mixture with 
this acid, and if the proportions be rightly adjusted, great de- 
crease of temperature is observed. It attracts watery vapor 
rapidly from the atmosphere, and is therefore used to promote 
evaporation by the air pump. 

It is said that, in the course of a month, sulphuric acid will absorb water 

486. Hyposulphuric acid. 

487. Origin of the name, oil of vitriol, &c. 

488. Properties cf sulphuric acid, &c. lis affinity for water, &c. 



SULPHURIC ACID. 189 

enough from the air, to double its weight ; and that the affinity is not satis- 
fied till the weight of the acid is augmented six fold. By reason of this 
affinity, sulphuric acid corrodes organic substances powerfully, causing 
their oxygen and hydrogen to unite and form water, while their carbon re- 
mains. It is on this account that this acid often appears deeply colored ; 
the color arising from the carbon of minute portions of vegetable water 
which have fallen in and been decomposed. Wood may be stained black 
by washing it with very dilute sulphuric acid, and then warming it so that 
the water may be dissipated and the action of the acid favored by the heat. 
Water acidulated with this acid, may also be used as a sympathetic ink, let- 
ters formed with it being rendered apparent on warming the paper. It dis- 
solves minute portions of charcoal and sulphur. The former communicates 
to it a blue green, or brown tinge and the latter a pink or brown; the color 
depending in each case on the quantity dissolved. 

489. Its strength may be tested by its specific gravity or, by 
ascertaining the quantity of carbonate of soda required to neutral- 
ize a known quantity of the acid ; 100 grains of the alkali will 
saturate 92 of pure acid. 

Ordinary sulphuric acid freezes at 15°, F. below zero. Its 
boiling point is 620°, F. 

491. The strongest sulphuric acid which can be prepared by the ordinary 
method is a hydrate, still containing one atom of water to one atom of acid. 
But it can be procured perfectly anhydrous by means of fuming sulphuric 
acid. This substance is the result of a very old process, still in use at Nord- 
hausen, in Germany. 

It is heavier than the common sulphuric acid and emits dense white fumes 
when exposed to air, especially if the atmosphere be moist. I 1 consists of 
acid and water, in such proportions that it may be considered a compound 
of one equiv. of anhydrous, and one of hydrated sulphuric acid. The an- 
hydrous acid being volatile below 122°, while the hydrous requires a temper- 
ature of 620°, it is easy to separate them by distillation at a very gentle heat. 

The anhydrous acid passes over as a perfectly transparent and colorless 
vapor and is condensed in the cool receiver, into a white and crystaline, or 
a transparent, glassy solid, according to the rapidity of cooling. — It is liquid 
in summer, unless artificially cooled. — It has a greedy attraction for water, 
combining with the moisture of the air and forming dense white fumes if 
exposed ; and if thrown into water it evolves great heat causing a hiss- 
ing and boiling like red hot iron. 

492. Natural History. Sulphuric acid occurs abundantly in 
nature in combination with earths, forming salts, of which the 
most plentiful are sulphate of lime, (gypsum or plaster of Paris,) 
and sulphate of baryta, (heavy spar ;) but it is seen seldom in an 
uncombined state, except near volcanoes. A large deposit of 
sulphur in Java in the crater of an extinguished volcano is the 
source of a stream of diluted acid, which in the rainy season flows 
down the mountain, destroying the vegetation along its banks. 

Professor Eaton mentions a pond near Rochester, N. Y. the waters of 
which, especially in a dry season contain some quantity of it. This acid, 
or any of its soluble salts can be detected in solution, by the addition of 

489. Tests of the strength of this acid. Freezing and boiling points. 

491. Anhydrous sulphuric acid. How procured ? Separation of the hy- 
drous acid. Properties of the anhydrous acid. 

492. Natural history. Tests of sulphuric acid. 



190 SULPHUR. 

solution of hydrochlorate of baryta when a heavy white precipitate will be 
formed, which is insoluble in acids and alkalies. 

493. Hydrous Sulphuric acid, which is the common acid of commerce is 
obtained by the following process : apartments being prepared, lined with 
sheet lead, and 8 parts of sulphur to 1 of nitre (saltpetre) broken into fragments 
are put upon iron plates. The mixture being inflamed, the door is closed. The 
floor is covered with water to the depth of some inches, which water absorbs 
the acid as fast as it is formed. The acidulated water is drawn off and con- 
centrated by heat, in leaden boilers until found to be of the proper specific 
gravity. 

Rationale. The process of the combustion is the formation of sulpliurous 
acid from the sulphur and deutoxide of nitrogen from the nitre. The latter 
combining with the oxygen of the air is changed into nitrous acid. The 
sulphurous and nitrous acids then combine with the watery vapor, and form 
a crystaline solid, composed of sulphuric acid, hyponitrous acid, and water. 
When this solid drops into water, it is instantly decomposed, the sulphuric 
acid being retained in the water, and nitrous acid and deutoxide of nitrogen 
escape. The nitrous acid thus set free, as well as that formed by the deu- 
toxide and oxygen of the air,again combines with the moist sulphurous acid, 
and forms the solid, which sinks to the water and is again decomposed. 
This process continues until the whole of the sulphur and nitre is changed in- 
to sulphuric acid, and absorbed by the water on the floor of the leaden cham- 
ber. 

Sulphur and Hydrogen. 

494. Hydro-sulphuric or Sulphuretted Hydrogen* consists of 
1 sul.=76-fl hyd.=l. equiv. 17. This is a gas ; formed by heat- 
ing sulphur in hydrogen, or by bringing sulphur and hydrogen 
together in a nascent state. 

Fig. 96. Let a portion of sulphur be put into a vessel, (Fig. 

96,) to the neck of which is fitted a bag of hydrogen 
iSras ; as the sulphur is heated it volatilizes, and its vapor 
rising unites with the hydrogen to form sulphuretted 
hydrogen. The gas may be collected over water. 

495. Its specific gravity is 1.18, a little more 
than that of atmospheric air ; it requires a pres- 
sure of 17 atmospheres to reduce it to the liq i id 
state. It is a colorless gas, of a most fetid o \ 
as may be perceived in putrid eggs, or the 
washing of a gun-barrel. Its taste also is un- 
pleasant, of which the water of sulphuretted 
springs is an example. It is poisonous even 
when mixed with a large quantity of air. Small 
birds were destroyed by an atmosphere contain- 
ing TsVo part of this gas. It does not support combustion, but 

* Sometimes called hydro-thionic acid, from the Greek hudor, water, and 
theion, sulphur. 

493. Hydrous sulphuric acid. Rationale. Sulphate of ammonia. 

494. Combinations of sulphur with hydrogen. 

495. Nature, and formation of sulphuretted hydrogen. Properties. 




SULPHUR. 



191 



burns with a pale blue flame ; the products of its combustion are 
water and- sulphurous acid. It also explodes on being ignited, 
when mixed with air, or oxygen. 

496. Potassium, tin, and some other metals decompose this gas when 
healed in it, uniting with the sulphur and liberating the hydrogen. Elec- 
tric sparks, or a platinum wire ignited by galvanism, will also decompose 
it. In these experiments, the hvdrogen evolved is equal in bulk to the hy- 
dro-sulphuric acid decomposed. 

Hydro-sulphuric and sulphurous acids mutually decompose each other, 
the oxygen of the one uniting with the hydrogen of the other, and the 
sulphur of both being deposited. Nitric acid poured into a phial of this 
gas, decomposes it by furnishing oxygen ; sulphur is deposited, and water, 
and deutoxide of nitrogen are formed. Water at 60° F., if freed by boiling, 
from other gases, will absorb about its own bulk of this gas, and afford a 
solution which has the odor, taste, and chemical action of the gas itself, 
and may therefore be used as a test. This solution is ven easily decom- 
posed by substances which yield oxygen, and even by e^n are to air; the 
oxygen uniting to the hydrogen of the hydro-sulphuric acid, and the sul- 
phur being deposited. This cause accounts for the constant deposition of 
sulphur from the water of sulphuretted springs. 

497. Hydro-sulphuric acid is an important test for metals, in 
solutions of which, it produces precipitates of metallic sulphur- 
ets ; these precipitates are of different colors, by which we are 
enabled to ascertain what metal is present. The gas acts also 
on many insoluble metallic compounds ; thus, white paint, (car- 
bonate of lead,) and the cosmetic pearl white, (oxide of bismuth,) 
are rendered black, owing to the formation of the black sulphur- 
ets of lead, and of bismuth. At sulphuretted springs, some lu- 
dicrous changes of complexion have occasionally happened to 
ladies beautified with pearl white. 

Fig. 97. The acetate of lead, 

in solution, is color- 
less, but let a drawing 
be made with it in this 
state, and then expos- 
ed to the action of a 
stream* of hydro-sul- 
phuric acid gas, (Fig. 
97,) the lines will be- 
come black, as if made 
with a lead pencil. 

This gas also tar- 
nishes gold and sil- 
ver, its sulphur 
combining with 
. Jthose metals to 
sulphurets. 




form 



* The stream of gas is invisible, though represented in the figure to aid 
in understanding its design. 

496. Decomposition. Absorption by water. 

497. Action on meta]?, and metallic compounds. 



192 SULPHUR. 

Chlorine may be used to purify an atmosphere contaminated with 
sulphuretted hydrogen. 

498. Hydro-sulphuric acid, reddens litmus paper, and com- 
bines with the fixed alkalies, and with ammonia ; its relations 
to the metallic oxides are perfectly analogous to those of the 
other hydracids. 

Liquid hydro-sulphuric acidy Mr. Faraday condensed this gas 
under a pressure of 17 atmospheres, so as to form a limpid and 
oily fluid 

499. Hydrosulphurous acid, called lisulphuretted hydrogen, 
is a yellow, viscid, semifluid, heavier than water, and having, 
in a lower degree, the same odor and taste as hydrosulphuric 
acid. It is easily decomposed by heat into sulphur and hydro- 
sulphuric acid. It contains 2 atoms of sulphur, to 1 atom of hy- 
drogen. 

500. Chloride of sulphur. This is a compound of one equivalent of each 
constituent, and is formed, directly, by passing chlorine over flowers of sul- 
phur gently heated. It is a volatile liquid of a red color, when seen in 
mass, but greenish yellow, when viewed in a thin stratum. It decomposes 
water rapidly, the chlorine taking the hydrogen of the water ; at the came 
time sulphur is deposited, and sulphurous and sulphuric acids are formed. 
Its vapor also decomposes the moisture of the air, giving fumes which affect 
the eyes powerfully, and which probably consist of the same acid products. 

Bromide of sulphur is a red, volatile, oily liquid, which decomposes water 
with great violence, and which is obtained by the direct action of bromine 
on sulphur. It is decomposed by chlorine, and chloride of sulphur is 
formed. 

Iodide of sulphur is likewise formed by direct action of its elements, aided 
by heat. It is a dark solid and is decomposed by heat. 

501. There is only one known compound of sulphur and car- 
bon. It contains 2 equivalents of sulphur, and 1 of carbon, and 
is therefore a hisulphuret of carbon. This substance, some- 
times called alcohol of sulphur, is obtained by passing vapor of 
sulphur over charcoal, heated red hot in a porcelain tube. It is 
to be conducted into a vessel of water, at the bottom of which, 
as it is heavier than water, it collects. It is a transparent liquid, 
of great refracting power, an acrid ond pungent tas>te, and dis- 
gusting odor. It boils at 110° Fahrenheit, and evaporates so 
rapidly at common temperatures, as to cause great cold. It 
burns with a blue flame, producing sulphurous and carbonic acid 
gases. It dissolves sulphur, phosphorus, and iodine, with the last 
giving a beautiful pink solution. Chlorine decomposes it, and 
unites with the sulphur. It will not mix with water, but dis. 

498. Acid properties. Liquid hydro-sulphuric acid. 

499. Hydro-sulphurous acid. 

500. Chloride, bromide, and iodide of sulphur. 

501. Bi-sulphuret of carbon. Properties. Hydroxanthic acid. 



SELENIUM. 193 

solves readily in alcohol and ether, from which solution water pre- 
cipitates it. When an alkali is put into the alcoholic solution, 
it becomes neutralized, owing to the formation of a new acid, 
which has been called hydroxanthic acid, from the yellow color 
of its salts. This latter acid appears to consist of carbon, sul- 
phur, and hydrogen, the hydrogen and an additional dose of 
carbon, being derived from the alcohol. 

502. Selinium. — Equiv. 40. Sp. Gr. 4.32. Selenium was 
discovered by Berzelius in 1818. It had been observed, by a 
manufacturer of sulphuric acid at Fahlun, in Sweden, that the 
sulphur, after sublimation, deposited a reddish mass. This was 
submitted to the examination of the Swedish Chemist, who 
obtained, by analysis, a very minute proportion of an apparently 
new substance, the remainder of the mass being a compound 
of mercury, tin, arsenic, lead, copper, zink, iron, and sul- 
phur. This new substance, Berzelius named selenium, from 
the Greek, selene, the moon (on account of its resemblance to 
the metal tellurium, so called from tellus, the earth.) The sub- 
stance in which the sulphur and selenium were thus found uni 
ted, was iron pyrites, (sulphuret of iron,) from the mines of 
Fahlun. Selenium has since been found in combination with 
minerals in the Hartz mountains in volcanic products of the 
Lipari islands and in pyrites of the isle of Anglesea in England. 
It was regarded, by its discoverers, as a metal, but being an im- 
perfect conducter of heat and electricity, it appears to belong to 
the class of simple non-metallic elements. 

503. Physical and chemical properties. It is solid at common 
temperatures, brittle, opake, and inodorous; at 212° Fahrenheit, 
it begins to liquefy, and fuses at a temperature a few degrees 
higher. If partly cooled when in this state, it appears like wax, 
and may be drawn out by the fingers, into long, transparent, 
elastic threads, which appear red by transmitted light, but grey, 
and of a metallic brilliancy, when seen by reflected light. At 
650° Fahrenheit it volatilizes, becoming a yellow vapor, suddenly 
cooled, produces a red powder, resembling the flowers of sulphur, 
except in color. If sublimed in the air, without taking fire, its 
vapor is red and without odor. But when heated in the flame 
of a lamp, heightened by a current of air from a blow pipe, it 
tinges the flame a light blue color, and emits a strong odor, re- 
sembling that of decayed horse-radish, in which property it re- 
sembles tellurium. In many of its properties, selenium resem- 

502. Discovery of selenium. Origin of the name. With what substances 
united, and where found. Why not classed among the metals ? Proper- 
ties of selenium. 

503. Physical and chemical properties. 

17 



194 SELENIUM AND OXYGEN. 

bles sulphur ; and in its specific gravity and metallic lustre, 
it resembles metals. 

504. Selenium and Oxygen. Selenic Acid. Seieni. l=40-|-ox. 3=24. 
Equiv. 64. Selenic acid may be obtained by dissolving 1 part of selen- 
ium, in 3 parts of nitric acid, and boiling the mixture. The selenium de- 
composes the nitric acid, and a solution of selenic acid is formed ; this may 
be evaporated to dryness, and then appears as a white mass, which may 
be sublimed on raisins the temperature; the color of the vapor resembles 
that of chlorine. Selenic acid has a sour taste, reddens vegetable blues, 
and has a strong affinity for salifiable bases. It powerfully attracts water, 
and like sulphuric acid, gives out much heat when mixed with it. When 
exposed to heat, it volatilizes without any decomposition. When heated 
with hydro-chloric acid, seleaious acid and chlorine gas are evolved, and 
the selenio-hydro-chloric acid, like the nitro-hydro-chloric, (aqua regia,) 
dissolves gold. Selenic acid also dissolves gold, but not platinum. 

505. Selenious Acid. Sel. l=40-f-ox. 2 = 16. Equiv. 56. When selenium, 
heated to its boiling point in a close vessel, is supplied with a current of 
oxygen gas, it burns with a pale, blueish green flame; selenious acid sub- 
limes, and if condensed in a cool receiver, will form long, striated, prisma- 
tic crystals. Its taste is sour, and somewhat burning; it is readily decom- 
posed by substances which have a strong affinity for oxygen. Its affinity 
for water is such, that it attracts it from the air. It was discovered by 
Berzelius, and being until recently, supposed the only acid of selenium, was 
termed selenic acid. But since an acid compound is now known to exist, in 
which selenium unites with a higher proportion of oxygen, the latter must 
be considered as the true selenic acid. 

506. Oxide of selenium. Seleni. l=40-|-ox. 1=8. equiv. 48. The com- 
position of this substance is somewhat doubtful, though it is supposed to 
contain 1 atom of oxygen and 1 of selenium. It is formed by heating sele- 
nium in a close vessel with atmospheric air. 

507. Proto-chloride of selenium may be obtained by passing chlorine gas 
over selenium; it is a liquid of a brown color, heavier than water. It is 
decomposed by water, forming muriatic and selenious acids. Per-chloride 
of selenium is obtained by adding chlorine to the proto-chloride. 

The Bromide of Selenium was obtained by Serullas, by causing selenium, 
in minute portions, to be brought in contact with bromine, combination en- 
sued with a disengagement of heat. At the common temperature, it was 
solid, orange colored, and soluble in water. 

Hydro-selcnic acid, or Seleniuretted hydrogen is a compound of 1 atom of 
selenium=40, and 1 of hydrogen=l, making its equivalent 41. Its discov- 
erer, Berzelius, found it to be, in many of its properties, similar to sulphu- 
retted hydrogen. Silliman suggests, that the noxious properties of the lat- 
ter compound may be often increased, by the presence of selenium, as sul- 
phur is often contaminated with it. Hydro-selenic acid may be obtained 
by dissolving seleniuret of iron in muriatic acid. Its solution reddens litmus 
paper, and gives a brown tint to the skin. It is readily decomposed by the 



504. Composition, and mode of obtaining selenic acid. Properties. 
Selenio-hydrochloric acid. Selenic acid with metals. 

505. Composition and formation of selenious acid. Properties. Salts. 
Discovery and former name. 

506. Composition and formation of the oxide of selenium. 

507. Compounds of selenium with chlorine. Bromide of selenium. Hy- 
dro-selenic acid. Phosphuret of selenium. Sulphuret of selenium. 



TABULAR VIEW OF CHEMICAL ELEMENTS. 



195 



action of air and water, and gives a red color to moist substances. It acts 
injuriously on the animai system. 

Phosphuret of selenium is obtained by bringing selenium into contact with 
phosphorus, when in a state of fusion. It is inflammable and very fusible. 
Sulphuret of selenium, as obtained by Berzelius, -was an orange colored pre- 
cipitate, formed after conducting hydro-sulphuric acid into a solution of se- 
lenic acid. 

508. Having considered the non-metallic elements, with the 
combinations which they form with each other we will give a 
tabular view of the same, according to the arrangement we have 
adopted; viz; the division into two classes of electro-positive, 
and electro-negative elements. These elements exist in the 
three different states of gaseous or ariform, volatile, and fixed, 
as represented on the table. 

TABLE 1. 



NON-METALLIC ELEMENTS. 



Aeriform. 



Volatile. 



Fixed, or 
Solid. 



Electro-Negative. 
Oxygen 



Equiv. 



Electro-Positive. 



Equiv. 



Chlorine 36 

Bromine 75 

Iodine 124 

Flourine 10 



Hydrogen 1 

Nitrogen 14 



Sulphur 16 

Phosphorus.. 12 

Selenium 40 

Carbon 6 

Silicon 8 

Boron 8 



509. The binary compounds of the basic non-metallic elements 
are arranged in the following table, under three divisions, viz. the 
acid, the alkaline and the neutral. The proportions are given, in 
which their component parts unite, with the equivalent number 
of each, showing the ratio in which their binary compounds will 
combine with other bodies. 

TABLE II. 

BINARY COMPOUNDS OF THE NON-METALLIC ELEMENTS. 



C^ added to 

1 Chlorine 

Ditto 

Ditto 

Ditto 



1 Oxygei 

4 Ditto. 

5 Ditto 
7 Ditto 



ACID. a 

Electro- Negative. kj 



Chloric acid 76 

Per-Chloric acid 92 



* « 2 NEUTRAL. ij 

^ Protoxide of Chlorine 44 
1*3 Peroxide of Chlorine G3 



508. Repeat the names and equivalents of the Electro-negative and Elec- 
tro-positive non-metallic elements with the state in which they are obtained. 

509. What are the binary compounds of these elements, and their equiv- 
alents? Which are acid, which alkaline and which neutral ? 



196 



TABLE OF CHEMICAL ELEMENTS. 



ill 

3 §, ACID. g, i g S 3 

bq added to &q Electro-Negative. fcj cq (^ 

1 Bromine 5 Oxygen Bromic acid 115 

Ditto 1 Chlorine Chloride of Bromine 111 

1 Iodine 5 Oxygen Iodic acid 164 

1 Hydrogen 1 Oxygen Water 9 

1 Ditto 2 Ditto Protoxide of Hydrogen 17 

1 Ditto 1 Chlorine Hydro-chloric acid 37 

1 Ditto 1 Bromine Hydro-bromic acid 76 

1 Ditto 1 Iodine Hydro-iodic acid 125 

1 Ditto 1 Flourine Hydro-fluoric acid 11 

1 Nitrogen 1 Oxygen Protoxide of Nitrogen 22 

1 Ditto 2 Ditto Deutoxide of Nitrogen 30 

1 Ditto 3 Ditto Hypo-nitrous acid 38 

1 Ditto 4 Ditto Nitrous acid 46 

1 Ditto 5 Ditto Nitric acid 54 

1 Ditto 4 Chlorine »».» .....£ Chloride of Nitrogen 158 

1 Ditto 3 Iodine - gjodine of Nitrogen 386 

1 Ditto Bromine Ammo-bq Bromide of Iodine (?) 

1 Ditto 3 Hydrogen nia. 17 

1 Carbon 1 Oxygen Carbonic oxide 14 

1 Ditto 2 Ditto Carbonic acid 22 

2 Ditto 3 Chlorine Perchloride of Carbon 120 

1 Ditto 1 Ditto Proto-chloride of Carbon 42 

1 Ditto 2 Hydrogen Subcarburetted Hyd. 8 

2 Ditto 2 Ditto Percarburetted Hyd. 14 

2 Ditto 1 Nitrogen Cyanogen 26 

1 Boron 2 Oxygen Boracic acid 24 

1 Ditto 2 Chlorine Chloride of Boron 80 

1 Ditto Flourine Fluoride of Boron 

1 Silicon 1 Oxygen Oxide of Silicon 16 

1 Ditto Chlorine Chloride of Silicon (?) 

1 Ditto 1 Flourine Fluo-silicic acid gas 19 

1 Phosphorusl Oxygen Phosphorous acid 20 

1 Ditto 2 Ditto Phosphoric acid 28 

2 Ditto 1 Ditto Hypo-phosphorous acid 32 

1 Ditto 1 Chlorine Proto-chloride of Phoi. 48 

1 Ditto 2 Ditto Per-chloride of Phos. 84 

Ditto Bromine Bromide of Phos. (?) 

Ditto Iodine Iodine of Phos. 

1 Ditto 2 Hydrogen Proto-phosphuretted Hyd. 14 

1 Ditto 1 Ditto Per-phosphuretted Hyd. 13 

1 Sulphur 2 Oxygen Sulphurous acid 32 

1 Ditto 3 Ditto Sulphuric acid 40 

1 Ditto 1 Ditto Hypo-sulphurous acid 24 

2 Ditto 5 Ditto Hypo-sulphuric acid 72 

1 Ditto 1 Hydrogen Sulphuretted Hyd. 17 

2 Ditto 1 Ditto Bi-sulphuretted Hyd. 33 

1 Ditto 1 Chlorine Chloride of Sulphur 62 

Ditto Bromine - Bromide of Sulphur (?) 

Ditto Iodine Iodide of Sulphur (?) 

Ditto Carbon Bi-sulphuret of carbon (?) 

1 Selenium 3 Oxygen Selenic acid 64 

1 Ditto 2 Ditto Selenious acid 56 

1 Ditto 1 Ditto Oxide of Selenium 48 

Ditto Chlorine Chloride of Selenium (?) 

1 Ditto 1 Hydrogen Hydro-selenic acid 41 

Ditto Phosphorus Phospburet of Selenium (?) 

Ditto Sulphur • . Sulphate of Selenium (?) 

We see that ammonia is the only alkaline compound of this class of substances. 



METALS. 197 



METALS. 

OR THE SECOND CLASS OF ELECTRO-POSITIVE 
ELEMENTS. 

CHAPTER XXI. 

GENERAL OBSERVATIONS UPON THE METALS. FIRST CLASS OF 

METALS, OR THOSE WHICH FORM ACIDS WITH OXYGEN. 

5 10. The metals vary greatly among themselves in their phys- 
ical properties. Some, as gold and platinum, are the heaviest sub- 
stances known ; while others, as sodium and potassium are 
lighter than water. Mercury is liquid at the common tempera- 
ture and can be solidified only by cold far below that of the 
freezing point of water ; but platinum remains solid even under 
the influence of the most intense heat. In their chemical affini- 
ties, metals differ greatly. Potassium and sodium have so great 
an attraction for oxygen, that they become oxidized from mere 
exposure to the air ; while silver and gold can with difficulty be 
made to unite with oxygen. 

511. The distinctive characters of the metals are as follows ; 
1st. They are all good conductors of electricity and heat ; the 

former passes through them instantaneously, the latter progres- 
sively, though rapidly. 

2d. They are positive electrics, that is they go to the negative 
pole in the galvanic series, when combined with oxygen, chlorine, 
iodine, bromine, or sulphur ; and their oxides have the same des- 
tination, when combined with acids. 

3d. They are opake ; they reflect the light powerfully, and 
with a peculiar glitter, termed the metallic lustre. This pro- 
perty is retained by the metals when divided into the minutest 
particles. 

4th. Though good conductors, they are bad radiators of heat. 

5th. They are fusible at different degrees of heat ; and when 
melted retain their lustre and opacity. 

6th. They possess in different degrees a peculiar tenacity, 
which renders them malleable and ductile, or capable of being 
extended under the hammer or drawn into wire. 

7th. They are capable of combining with oxygen, thus 
forming oxides that bear a metallic appearance ; those oxides, by 
uniting with acids, saturate them and form salts. 

510. Variety in the properties of metals. 

511. General characteristics. 

17* 



198 METALS. 

512. Of all substances in nature, none have, from the earliest 
ages of the world, more attracted the attention of mankind than 
the metals. To the experiments of the alchemists, in their at- 
tempts to transmute the baser metals into gold and silver, the 
science of chemistry owes its existence. Yet notwithstanding 
the researches of the alchemists, so late as the fifteenth century, 
only seven metals, appear to have been discovered ; viz. gold, 
silver, iron, copper, lead, mercury, and tin, with a few ores and 
combinations with other metals. 

513. The metals have been variously classified by different 
writers. It has been common to arrange them according to 
their relative affinites for oxygen, which vary so much, that while 
one class part with oxygen, by application of a slight degree of heat, 
another class retain it so strongly that it requires the greatest 
power of the voltaic pile to effect their disunion. But though 
the extremes, in respect to affinity for oxygen, may widely differ, 
there are many metals included between those which part easily 
with oxygen and those which strongly retain it which renders 
it difficult to class them upon this principle. 

It is well for science, that its foundations stand firm, though some of its 
superstructures may fall. Though in mental and moral science, classifica- 
tion varies with almost every writer, yet truth is immutable, and those va- 
rious classifications are hut as so many mirrors in which she is exhibited in 
different lights. The same is true in the physical sciences ; one mode of 
classification brings out in bold relief one set of properties, and another 
mode brings into light other properties, which, but for this kind of distinc- 
tion, might not have been duly observed. 

Classification. 

514. We shall arrange the metals into four classes. 
1st. Those which form acids with oxygen. 

2d. The alkaline metals, or those whose oxides are either fix- 
ed alkalies, or alkaline earths. 

3d. Earthy metals, or those whose oxides are earths. 

4th. Metals whose oxides are not regarded as earths or alka- 
lies. 

515. The Metals of theirs* class, or those which form acids 
with oxygen, are 13 in number, as follows, viz. arsenic, anti- 
mony, columbium, litanium, chromium, molybdinum, tellurium, 
tungsten, vanadium, uranium, manganese, cobalt, and tin. 



512. Early attention of mankind to this class of substances. 

513. Various classifications of metals. 

514. Division of metals adopted. 

515. Metals of the first class. 



ARSENIC. 199 

516. Arsenic, — Equiv. 38. The name is supposed to be deri- 
ved from the Arabic, arsanak, signifying strong and deadly quali- 
ties. It was noticed in combination with sulphur, by the Greek phi- 
losopher Dioscorides under the name of sandarac. In 1773, Brandt 
discovered it to be a distinct metal. The substance usually call- 
ed arsenic is the arsenious acid or white oxide of arsenic. Arse- 
nic has a metallic lustre, resembling that of polished steel ; it is 
brittle and granular in its texture. Exposed to the air it be- 
comes tarnished, and covered with a blackish substance, which. 
appears to be a protoxide of arsenic. Thrown upon burning 
coals, arsenic burns with a blue flame, volatilizing in the form 
tf white vapors, and with a strong smell of garlic. It is some- 
times found pure and native, but it is more commonly combined 
with the ores of other metals, especially iron and cobalt ; by 
roasting these ores, the arsenic, which is very volatile, vaporizes 
and condenses in receivers prepared for the purpose. 

517. Two compounds of arsenic and oxygen are known to 
exist. 

Arsenic. Oxygen. 

Arsenious acid, 38 or 1 equiv. 12 or 1§ equiv. 

Arsenic acid, 38 " « 20 or 2£ equiv. 

518. Arsenious Acid, sometimes called the white oxide of arse- 
nic, and rats bane, is a white substance, offensive to the taste, 
and a deadily poison, not only when taken into the stomach, 
but when applied to a wound, or when its vapor is inhaled. 
Though soluble in warm water, a portion of the acid, in the 
form of a white powder, will be found supended as the liquid 
becomes cool. This circumstance has often led to the detection 
of attempts to destroy life by this poison. 

There are different tests by which the presence of this mineral may be 
detected. In the solid state, it may be kno^n, in the open air, when heated, 
by its peculiar odor, like that of garlic. In solution it forms a white pre- 
cipitate with lime water ; and a yellow sulphuret of arsenic with hydro-sul- 
phuric acid. Sulphuret of potassium, and sulphuret of sodium precipitate 
this substance in yellow flakes ; but it is necessary to add some drops of 
acetic or hydro-chloric acid that may unite with the base of the sulphurets, 
otherwise there will be no precipitate. Writers on medical jurisprudence 
by omitting this circumstance, have led to errors in attempts to detect the 
presence of arsenic. In so important a trial as that of determining the 
presence of arsenical poison in the stomach of a deceased person, there 
should be a resort to various tests, and therefore while one portion of the 
contents of the stomach is subjected to the action of one test, other portions 
should be tried by other means. The nitrate of silver precipitates a white 
powder in solution of arsenical compounds, which, with ammonia, forms a 

516. Derivation of the word arsenic. Discovery. Mode of obtaining 
the metal. Properties. Native state. 

517. Compounds of arsenic and oxygen. 

518. Synonymes of arsenious acid. Properties. Various tests. 



200 ANTIMONY. 

yellow arsenite of silver. Ammoniacal sulphate of copper produces an ap- 
ple green precipitate, which is the arsenite of copper or Scheele's Green. The 
effect of arsenic upon the animal system is speedy and violent. The per- 
hydrate of iron with ammonia, is one of the best antidotes for this poison. 
Owing to the property of this substance of preserving dead bodies from de- 
cay, the stomach and intestines of those who have been poisoned with it 
have been found undecomposed some years after death. 

519. Arsenic Acid may be obtained by boiling arsenious acid with nitric 
acid, which yields a portion of its oxygen, giving off nitric oxide. This acid 
has a sour metallic taste, reddens vegetable blues, and forms with alkalies 
neutral salts, called arseniates. 

520. Arsenic in powder, takes fire in chlorine gas, forming chloride of ar- 
senic. It unites with iodine by a gentle heat, forming the iodide of arsenic, 
which is a deep red compound. Bromine, by mere contact with metallic 
arsenic, burns with vivid light and heat, forming a volatile bromide of arse- 
nic. Arseniuretted hydrogen is highly destructive to animal life. A German 
philosopher, M. Gehlen, in making experiments with it, inhaled its vapor, 
and died in consequence, with intense suffering. It extinguishes combus- 
tion, but is itself kindled by burning bodies, and burns with a blue flame. 
The Sulphurets of arsenic exist as natural minerals. The red sulphuret is 
known by the name of realgar; a yellow sulphuret is called orpiment ; this 
is the basis of the paint known as king's yellow. The sulphurets of arsenic, 
though poisonous, are less so than the acids. 

521. Jlntimony. — Equiv 44. The name of this mineral is de- 
rived from anti, against, and monakos a monk, the improper use 
of it as a medicine, by a German monk, in the 15th century, 
having caused the death of many of his fraternity. What is 
termed crude antimony in commerce, is the native sulphuret of 
this metal. 

In its pure state, antimony is a shining metal, of a silvery white color, 
a scaly texture, brittle, and gives off a peculiar odor, on being rubbed. It 
melts below .red heat ; and when suffered to cool slowly, often presents 
upon its surface marks of crystalization, resembling fern-leaves. It fuses 
at 810° F. and sublimes in dense white fumes, combining with oxygen. 
When in a state of powder it inflames spontaneously in chlorine gas, and 
burns with a bright white flame. The product is a liquid, which becomes 
solid on cooling. This chloride from its consistence was formerly called 
butter of antimony. The per-chloride is obtained by adding nitro-muriaiic 
acid, hydro-chloro-nitric, to antimony ; it is a volatile, fuming liquid. 

522. The Protoxide of antimony is obtained by dissolving in water, proto- 
chloride of antimony ; a white powder is precipitated called powder of alga - 
roth, which is a sub-chloride of antimony. A solution of potash beins: ad- 
ded to this powder, the chlorine combines with the potash, and the metal 
uniting with the oxygen of the water, forms the protoxide of antimony. When 
heated to redness in an earthen crucible, antimony disengages a thick 
white smoke, which being condensed, forms a white crystaline substance 

519. Mode of obtaining arsenic acid, its properties and salts. 

520. Combinations of arsenic with chlorine, iodine, bromine, hydrogen 
and sulphur. 

521. Supposed derivation of the name. Antimony of commerce. Pro- 
perties. Chlorides. 

522. Protoxide. 



COLUMBIUBI. 201 

formerly called argentine Jlowers of antimony ; this is similar in its composi- 
tion to the protoxide. 

523. Deutoxide of antimony. When metallic antimony is digested in 
strong nitric acid, the metal is oxidized at the expense of the acid, and a 
white hydrate of the peroxide is formed; on exposing this substance to a 
red heat, water and oxygen gas are disengaged, and the peroxide is reduced 
to a deutoxide. As this combines with alkalies, it has been called antimo- 
nious acid. 

524. The Peroxide or antimonic acid forms salts with alkalies called an- 
timoniates. It is changed by heat into the deutoxide. 

525. The Sulphuret of Antimony is found extensively as a native combina- 
tion ; it may also be prepared by art, by fusing antimony with sulphur, and 
the compound is, in all respects, similar to the native mineral. When this 
sulphuret is slowly roasted in a shallow vessel, it gradually loses sulphur, 
and attracts oxygen, and may then be melted into a glassy, semi-transparent 
substance, which is called the glass antimony. The medicine known as 
tartar emetic is a triple compound of tartaric acid, protoxide of antimony 
and potassa, called antimoniatcd tartrate of potassa. 

526. Alloys of antimony. Antimony may be made to com- 
bine with most of the metals. A very slight mixture not ex- 
ceeding the yo¥ °f tne whole mass is sufficient to destroy the 
ductility of gold, and even its fumes alone will produce that 
effect. Combined with lead, it becomes the alloy called type 
metal, which is used for printing types. 

527. As a medicinal agent, when properly employed, this 
metal is highly valuable. It was not, however, until long after 
its discovery that its nature seems to have been well understood. 
From its fatal operation in many instances, the French parlia- 
ment, early in the seventeenth century, at the suggestion of the 
medical faculty, proscribed the use of this medicine. This de- 
cree was, however, soon revoked and antimony again received 
in favor. 

528. Columbium. — Equiv. 144. This metal was discovered 
by Mr. Hachett of England in 1801, who detected it in a black 
mineral belonging to the British Museum, which had been sent 
by Gov. Yv inthrop from New London in Connecticut, to Sir 
Hans Sloane, founder of the museum. The new substance was 
named Columbium, by its discoverer, in honor of the country 
from whence it had been sent. The mineral from which co- 
lumbium is obtained is now found in Chesterfield, Mass. and 
Haddam, Conn. 

529. Professor C. U. Shepard succeeded in obtaining the metal, by the de- 

523. Deutoxide of antimony or antimonious acid. 

524. Peroxide, or antimonic acid. 

525. Sulphuret of antimony. Glass of antimony. Tartar emetic. 

526. Alloys of antimony. 

527. Medicinal properties. 

528. Discovery of columbium. Origin of the name, &c. 

529. Indentity of tantalum and columbium. 



202 TITANIUM. 

composition of the mineral. But this is one among the refractory metals 
which are extracted with difficulty from rare minerals. Their discovery 
reflects honor on those who have so industriously sought them out, and gives 
new interest to science : although this metal, hitherto, has not been ap- 
plied to any useful purpose in the arts. 

About two years after the discovery of columbium, Ekeberg a Swedish 
Chemist extracted the same substance from the mineral called tantalite, and 
supposing it to be a new metal he called it tantalum. In 1809, Dr. Wolias- 
ton proved that this was indentical with columbium, and tantalum was ac- 
cordingly stricken from the list of simple bodies. 

530. Columbium is of a dark iron color. It is very hard, in- 
soluble in acids, and soluble in alkalies. It unites with oxygen 
but in one known proportion, one equivalent of the metal, 144, 
being combined with one of oxygen 8=152. This compound, 
sometimes called the oxide of columbium, reddens litmus paper, 
and combines with salifiable bases, properties which are charac- 
teristics of acids. The salts of this acid are called columbates. 

531. Titanium. History. Discovered in 1781, by Mr. Gregor 
of Cornwall, England, in black sand ; but its character was not 
then fully ascertained. Afterwards, in 1795, Klaproth publish- 
ed an analysis of a crystalized mineral, known at that time as 
red schorl ; though he did not entirely succeed in reducing it to 
a metallic state he inferred that it was the oxide of a new metal, 
which he named titanium. In 1822, Dr. Wollaston discovered 
this metal in some minute copper-colored crystals, presented to 
him by the Rev. Dr. Buckland, who had found them in the slag 
of an iron furnace at South Wales. 

They conducted electricity, had a specific gravity of 5, 3, and were so 
hard as to scratch a polished surface of rock crystal. They become oxidiz- 
ed, by being heated with nitre, and were converted into a white substance, 
which was considered an oxide of titanium. Similar crystals of titanium 
have since been found at other iron works, where they have sometimes 
been mistaken for iron pyrites. In its purest native state, this metal is 
combined with a small portion of iron, which renders it slightly magnetic. 
It is infusible, tarnishes in the air, and is easily oxidized by heat. 

532. The protoxide of titanium is of a blue color, and is supposed to exist 
in the mineral called anatasse, but its composition and properties are doubt- 
ful. With lime and silex it forms the mineral called sphcne. 

533. The peroxide exists nearly pure in the mineral called titanite or ru- 
tile.. When pure, this oxide is nearly white; it possesses some acid pro- 
perties, and is sometimes called titanic acid. The oxides of titanium have 
been used in porcelain painting. Silliman states that titanium is found 



530. Properties of columbium and its combination with oxygen. Oxide 
of columbium. Its salts. 

531. History of titanium. Properties of crystals of titanium. Resem- 
blance to iron pyrites. Titanium combined with iron, &c. Properties of 
the metal. 

532. Protoxide. Anatasse. Sphene. 

533. Peroxide. Properties, &c. 



CHROMIUM. 203 

frequently in the primitive rocks of the United States. Its equivalent 
number is not fully known. 

534. Chromium. — Equiv. 32. So named from the Greek. 
kroma, on acconnt of its tendency to form colored compounds. 
It was discovered by the French chemist, Vauquelin, in analyzing 
the chromate of lead, a beautiful red mineral from Siberia. It 
is a white and brittle metal, susceptible of high polish, and only 
imperfectly fused at very high temperatures. It is not changed 
by air, but absorbs oxygen at a red heat. Sulphur, phosphorus 
and chlorine are the only combustible, non-metallic elements 
which combine with it. It exists in nature only in the state of 
a chromate or an oxide. 

535. Many of the gems owe their beautiful tints to this metal. 
Its acid gives the red color to the ruby : its oxide the green 
color to the emerald. Chromate of iron, is found in marble and 
serpentine, to which they are probably indebted for their beau- 
tiful variety of colors. New Haven and Milford in Connecticut, 
and Baltimore in Maryland, furnish fine specimens of chromate 
of iron. 

536. Protoxide of Chromium is a green, pulverulent substance, 
infusible, undecomposable by heat, and insoluble in water. It 
was discovered by Vauquelin. It may be obtained by decom- 
posing the chromate of mercury at a very high temperature. 
The mercury is disengaged in vapor, and the chromic acid re- 
solved into oxygen and the protoxide of chromium. This oxide 
is sometimes found on the surface of chromated lead; it is this 
which causes the green color of the emerald and many mag- 
nesian rocks. It is employed in the arts ; it is used in porcelain 
painting to give a fine green color ; and is the coloring used in 
artificial gems which are made to imitate the emerald. There 
is a brown oxide which some suppose to be a distinct substance 
composed of one equivalent of chromium and one of oxygen j it 
has been called chromous acid, and deutoxide of chromium. By 
others it is considered a mixture of green oxide and chromic 
acid. 

537. Chromic Acid exists, in nature, in combination with lead, 
forming the chromate of lead of Siberia and Brazil ; it imparts 
to the ruby its peculiar hue of dark red. It may be obtained 
from its concentrated solution in ruby red crystals. It is very 

534. Derivation of the name chromium. Discovery, properties, &c. 
Combination with oxygen, and non-metallic combustible elements. How 
found in nature ? 

535. Coloring properties, &c. 

536. Properties, discovery, and mode of obtaining protoxide of chromium. 
Its use. Brown oxide of chromium. 

537. Chromic acid. 



204? MOLYBDENUM. 

soluble in water, has a sour taste, and forms colored salts, called 
chromates, with alkaline bases, and metallic oxides. When ex- 
posed to strong heat, oxygen is disengaged, and the acid changes 
to the green oxide. It destroys the color of indigo, and most 
vegetable and animal coloring matters ; a property advanta- 
geously employed in calico printing, and which depends on the 
facility with which it yields its oxygen. It gives with mer- 
cury, a cinnibar red ; with silver, a carmine red ; with lead, 
orange yellow; with tin, green; and with borax, a beautiful 
emerald-green color. 

538. Fluo-chromic acid gas is disengaged, when a mixture of fluor spar 
and chromate of lead is distilled with sulphuric acid, in a leaden retort. 
This gas acts rapidly upon glass. Chromium forms a red gas with chlorine, 
called chloro chromic acid gas; it is obtained by the action of fuming sul- 
phuric acid on a mixture of chromate of lead, and chloride of sodium. A 
chloride of chromium, is obtained by transmitting dry chlorine over a mix- 
ture of chromium and charcoal, heated to redness in a porcelain tube. 
This chloride is a crystaline sublimale of a purple color. Sulphuret of Chro- 
mium is a dark gray substance, consisting of one equivalent of each of its 
elements. Phosphuret of Chromium is a porous substance, of a light gray 
color. 

539. Molybdenum. — Equiv. 48. The name of this mineral is 
from the Greek molubdaina, lead, it being at first confounded 
with black-lead, or plumbago as were all metals which are 
light, friable, soft, of a greasy feel, and which stain the fingers, 
or paper. Scheele first proved that plumbago is a carburet of 
iron, and molybdenum the sulphuret of a new metal. It has not 
been found pure, in a native state ; the sulphuret of molybdenum 
is common in the Alps, and Austria, and is found, in small 
quantities, in the primitive rocks of the United States. 

540. When the sulphuret of molybdenum is distilled in nitric acid, molyb- 
dic acid is obtained, in the form of a yellowish white, heavy powder. This 
being mixed with oil, and placed in a crucible lined with charcoal, is heated 
intensely, and the acid disengaging its oxygen, is reduced to a pure metallic 
state. It has never been obtained except in small globules of a gray color. 
It is among the most infusible metals. At the ordinary temperature, it has 
no action upon oxygen ; but at a red heat, it unites with it forming a white 
sublimate of molybdic acid. 

541. The protoxide of molybdenum is black, the deutoxide, or molybluous 
acid is a brown, and molybdic acid is yellowish-white. Berzelius slates that 
there are three chlorides of molybdenum. A native sulphuret of molybdenum, 
of a ruby-red color has lately been discovered. This metal has yet been of 
little use in the arts ; but its coloring properties are peculiar, and may, 
hereafter, be advantageously applied. 

538. Fluo-chromic acid gas. Chloro-chromic acid gas. Chloride of 
chromium. Sulphuret of chromium. 

539. Derivation of the name Molybdenum. By whom distinguished from 
plumbago ? In what state, and where found. 

540. How is it obtained ? Properties. 

541. Character of its oxides and acid. Chlorides. Sulphuret. Uses of 
the metal. 



TUNGSTEN. 205 

542. Tellurium. — Equiv. 32. Was discovered in 1782, by 
M. Muller, in the gold mines of Transylvania, and named by 
Klaproth, from Tellus, the earth, in accordance with the ancient 
method of naming the metals after the planets. Tellurium has 
been found in the state of an alloy, with gold, silver, lead, cop- 
per, iron, and sometimes with all these metals united.* It is 
brittle, of the color of tin, with some lustre. It fuses readily, 
and is the most volatile of all the metals, except osmium and 
mercury. When distilled in close vessels, it sublimes, and its 
vapor condenses into brilliant metallic drops. When heated in 
contact with the air, it oxidizes, and burns with a sky-blue 
flame, edged with green. It gives off a gray smoke, of a pun- 
gent, nauseous odor, resembling that of the vapor of selenium, 
and which has been compared to the odor of decayed horse- 
radish. This vapor condenses into a white oxide of tellurium. 
It unites both with alkalies and acids, to form salts. Tellurium 
is a rare mineral. Silliman supposes it exists in the town of 
Munroe in Connecticut. 

543. Telluretted Hydrogen gas may be obtained by mixing together oxide 
of tellurium, hydrate of potassa, and charcoal, at a red heat, and acting 
upon the mixture by dilute sulphuric acid. The combination of hydrogen 
and tellurium which ensues, is a gas which, lite sulphuretted hydrogen, 
manifests acid properties. It forms a claret colored solution with water, 
burns with a black flame, and deposits the oxide of the metal. 

54-4. Tungsten. — Equiv. 96. This metal was first discovered 
in Sweden ; its name signifies, in the Swedish language, heavy 
stone. It is the heaviest metal known, except iridium, gold, and 
platinum. 

The ores of this metal are tungsten or tungsiate of lime, yellow oxide of 
tungsten, and wolfram or tungstate of iron, and manganese. In these ores, 
tungsten exists in the state of tungstic acid, and has been found native in 
no purer form. The mineral is first decomposed in order to obtain the 
acid ; the latter, in the form of a whitish powder, is then made into a paste 
with oil, and heated intensely in a crucible, lined with charcoal. The pre- 
sence of small metallic globules, indicates the reduction of the metal. 

It is of an iron gray color, of a brilliant lustre, and so hard as 
scarcely to yield to the file. It is very infusible. 

545. The oxide of tungsten is formed by the action of hydrogen gas on 

* For the process of obtaining the metal from its ores, see the author's 
Die. of Chem., article Tellurium. See also Silliman's Elements, Vol. II. 
p. 160. 

542. Discovery of tellurium, and origin of its name. With what metal 
found ? Properties. White oxide of tellurium. Localities of tellurium. 

543. Telluretted hydrogen gas. 

544. Discovery of tungsten, &c. Origin of the name. Ores of this me- 
tal. How obtained from its ores ? Color &c. 

545. Oxide of tungsten. Tungstic acid. Chlorides. Localities of tung- 
sten ores. 

18 



206 MANGANESE. 

tungstic acid, at a low heat. It is of a dark chocolate color ; and when 
polished resembles copper. This oxide does not unite with acid to form 
salts. 

Tungstic acid is of a yellow color ; it has no action on litmus paper ; its 
acid properties are so feeble, that its salts are readily decomposed by most 
other acids. 

Tungsten unites in three proportions with chlorine, forming chlorides. 
The ores of tungsten have been found in the cobalt mines in Chatham, and 
Monroe in Connecticut. 

546. Vanadium. — Equiv. 68. It was recently discovered by M. Sefstrom, 
director of the school of mines at Fahlun in Sweden. It was named from 
Vanadis a Scandinavian deity. Its properties resemble those of chromium, 
with which it might easily be confounded. Professor Del Rio, many years 
since, supposing that he had found a new metal in the brown lead ore of 
Zimapan in Mexico, sent some specimens of it to the French chemists at 
Paris, who pronounced them to be mwrely impure chromium. Since the 
discovery of vanadium the opinion of Del Rio has been confirmed, and the 
ore pronounced to be a vanadiate of lead ; the same substance has been 
lately discovered in a mineral from Wanlockhead in Scotland. Like chro- 
mium, it appears to possess peculiar coloring properties. Vanadic acid is 
red, and fusible. The oxide is of a dark brown color. 

547. Uranium. — Equiv. 208. It was discovered in 1789, by Klaproth, 
and named from the Greek, uranos, the heavens. The ores which contain 
this metal, are very rare. Combined with carbonic acid, it forms chalcolite, 
or green mica. Its ores are reduced with difficulty, and it has only been 
obtained in small quantities. It is of a dark grey color, hard, and brittle. 
The protoxide is of a dark green color ; it unites with acids, forming salts 
of a green color. It is employed in the arts, for giving a black color to 
porcelain. The peroxide is of an orange color, and most of its salts have a 
similar tint. It is used for giving an orange color to porcelain. 

548. Manganese. — Equiv. 28. It is never found native in 
the metallic state, the substance known in the arts by this name, 
being an impure oxide. Owing to its great affinity for oxygen, 
it is usually found in nature combined with it, though sometimes 
in the state of a phosphate, and a sulphuret. 

"The black oxide of mansanesc was described by Scheele, in the year 
1774, as a peculiar earth ; Gahn subsequently showed that it contained a 
new metal, which he called magnesium, a term since applied to the metallic 
base of magnesia, and for which the words manganesium and manganum 
have been substituted.*' Turner. The pure metal may be obtained by heating, 
for an hour or two, over a powerful air furnace, a mixture of the black 
oxide, oil, and charcoal, in a black lead crucible ; on cooling the mixture, 
metallic masses will be found with the charcoal at the bottom of the cru- 
cible. 

549. This metal, in some of its properties, resembles iron ; it 



546. Vanadium. Its discovery and name. Mistake of the French chem- 
ists. Acid and oxide of vanadium. 

547. Discovery of uranium. Name. Ores. Properties. Compounds 
with oxygen. 

548. How is manganese found in nature ? By whom discovered. Orig- 
inal name. How obtained pure ? 

549. Properties. Action with air or oxygen, or with hydrogen, nitrogen, 
&c. Phosphuret. Chloride. 



MANGANESE. 207 

is of a gray color, very hard and brittle. It is very infusible, 
readily acted upon by air, tarnishing and at length crumbling 
into a brown powder. At the ordinary temperature, it has no 
action on atmospheric air, or oxygen gas ; but at a high temper- 
ature, it soon oxidizes. It is not acted upon by hydrogen, ni- 
trogen, boron, or carbon, and does not easily combine with sul- 
phur, though a natural sulphate of manganese exists. At a high 
temperature, it combines with phosphorus, forming a white, and 
brilliant phosphuret. It absorbs chlorine rapidly, forming a very 
soluble, greenish chloride. 

550. The protoxide, or green oxide of manganese, is obtained by igniting 
the deutoxide in contact with hydrogen or charcoal. Its rich green color 
on exposure to the air, changes to brown. 

The deutoxide, or brown oxide, remains when the peroxide is heated to 
afford oxygen gas. It is found in large native crystals, in the Hartz moun- 
tains. 

The 'peroxide, called also the black oxide, is that which, by heat, disen- 
gages half an equivalent (4 parts.) of oxygen, and is therefore commonly 
used for the purpose of obtaining oxygen gas. To obtain oxygen gas from 
the peroxide of manganese, it is sufficient to apply red heat to the latter, 
but if sulphuric acid be added to the peroxide of manganese, the presence 
of the acid appears to increase the disposition of the peroxide to give up its 
oxygen, by combining with the deoxidized manganese. This is a case of 
disposing affinity. This oxide occurs in large masses of an earthy appear- 
ance, and mixed with other substances, such as oxide of iron, carbonate of 
lime, and siliceous earth. It is sometimes found in groups of crystals, and 
is an essential ingredient in a mineral called black wad. 

551. A red oxide of manganese, supposed by some, to be a 
mixture of the peroxide, and the deutoxide, and by others, a def- 
inite, compound, imparts to glass or borax a beautiful violet 
color ; the amethyst owes its rich color to the presence of this 
oxide. 

If a mixture of 1 part of powdered black oxide of manganese, and 3 parts 
nitrate of potassa, be thrown into a red hot crucible, and continued there 
until no more oxygen is disengaged, a green-colored, fused mass is obtained, 
called mineral chamelion, from its property of assuming different colors. On 
putting this substance into water, a green solution is obtained, which soon 
passes into blue, purple, and red ; at length a broAvnish matter, the red 
oxide, subsides, and the liquid becomes colorless. These phenomena are 
explained as follows : the peroxide of manganese, when fused with potassa, 
absorbs oxygen from the atmosphere, and is thereby converted into manga- 
nesic acid, which unites with the alkali ; the changes of color, are owing to 
the combination of manganesic acid with different proportions of potassa. 
By evaporating the red solution rapidly, small, prismatic, purple crystals 
are obtained ; these are the manganesiate of potassa. 

There is also supposed to be a manganesious acid, or an acid with a small- 
er proportion of oxygen. The manganesiate of potash, being acted upon by 

550. Protoxide. How obtaned. Deutoxide. Peroxide. Use of sulphu- 
ric acid in the process for obtaining oxygen from the peroxide of manganese. 

551. Red oxide of manganese. Mineral chamelion. Manganesic acid, 
how formed ? Manganesious acid. 



208 COBALT. 

substances that attract oxygen, as alcohol, and carbonate of manganese, 
loses its red color, and becomes a green manganese of potash, the acid in 
the latter being reduced to the manganesiotts, containing but three equiva- 
lents of oxygen, while the manganesic contains four equivalents. 

552. Chlorine gas for chemical experiments, and liquid chlorine for 
bleaching, are usually obtained by the agency of the peroxide of manganese 
in combination with hydrochloric acid. The acid, consisting of one equiv- 
alent of chlorine and one of hydrogen, is decomposed by the loss of its hy- 
hydrogen, which, by uniting with one equivalent of oxygen given off by the 
peroxide of manganese, produces one equivalent of water. The chlorine 
being set free, passes off in a gaseous state. The loss of oxygen by the 
manganese, having converted the peroxide to a protoxide, the latter unites 
with an equivalent of undecomposed hydro-chloric acid, and forms a hydro- 
chlorate of the protoxide of manganese. Manganese unites with chlorine 
in two proportions, forming a pink colored proto-chloride, with one equiva- 
lent of each element ; and a per-chloride with one equivalent of manganese 
and four of chlorine. The latter is prepared by putting sulphuric acid into 
a solution of manganese, and then adding fused sea-salt. The hydrochloric 
and manganesic acids mutually decompose each other, producing water and 
the per-chloride of manganese ; the latter is a vapor, which at first appears 
of a yellowish green tint, but condenses into a dark colored liquid. When 
the per-chloride vapor is introduced into a flask, the sides of which are 
moist, the color of the vapor changes instantly, and a rose-colored smoke 
appears. Manganese combines with fluorine, forming a. fluoride of manga- 
nese, which at first appears in the form of a greenish yellow vapor. When 
mixed with atmospheric air, it assumes a beautiful purple red color. It 
acts on glass. On account of rendering glass colorless, the black oxide of 
manganese was formerly, called by the artists, glass -maker's soap. Accor- 
ding to Pliny it was used two thousand years ago. 

553. Cobalt, Equiv. 26. The name is derived from, Kobalas, 
the supposed demon who infests mines, impeding- the operations 
of the miners, and destroying their lives. Though employed in 
the fifteenth century for the purpose of coloring glass blue, it was 
not known to be a simple element until obtained from its ores 
by Brandt of Sweden, in 1733. It is hard, brittle, of reddish 
grey color, and weak metallic lustre. It is magnetic, a proper- 
ty which was formerly ascribed to the presence of some iron, 
but a magnetic needle has been made of pure cobalt. It is found 
in connexion with ores of iron and copper, but chiefly with 
arsenic. 

When the arsenical ore of cobalt is heated, the arsenic exhales in vapor, 
and the oxide of cobalt remains. This operation is carried on extensively 
in Saxony ; the labor being performed by criminals who are condemned to 
be thus slowly destroyed, for crimes which incur the punishment of death. 
The white oxide of the arsenic of commerce is mostly thus obtained. 

554. Protoxide of Cobalt, is formed when cobalt is slowly 

552. Process for obtaining chlorine by the aid of per-oxide of manganese. 
Chlorides and fluoride of manganese. Fluoride of manganese. 

553. Origin of the name Cobalt. Discovery. Properties. Ores. How 
obtained from the arsenical ore ? 

554. Protoxide of cobalt. Peroxide. Statement of M. Gmelin respect- 
ing the formation of cobaltic acid. Zatfre. Smalt. Powder-blue. Use 
of cobalt in the manufacture of porcelain. 



COBALT. 209 

oxidized by being heated in the open air. It is at first blue, 
gradually becomes darker, and an intense heat melts it into a 
blue-black glass. The Peroxide is formed by igniting the pro- 
toxide, and exposing it to the action of the oxygen of air ; it 
rapidly absorbs oxygen, becoming first of an olive-green color, 
and then black. By continued powerful heat a portion of oxy- 
gen is expelled, and the substance becomes again a protoxide. 

Though we hive classed cobalt with the metals which form acids with 
oxygen, there is some doubt as to the existence of a Cobaltic Acid. M. 
Gmelin from a solution of ammonia and nitrate of cobalt obtained crystals 
of a double salt, supposed by him to consist of nitrate, and cobaltate of am- 
monia, the latter consisting of cobaltic acid and ammonia. 

The Zaffire of commerce is an impure oxide of cobalt. Smalt 
is formed by heating the oxide of cobalt with a mixture of sand 
and potassa ; the result is a beautiful blue colored glass. This, 
when ground fine, is called powder blue ; it is used by laundress- 
es as a very delicate bluing for muslins and laces, in paper 
manufactories to give a blue tint to paper, and is employed in 
painting. Cobalt, being the only blue color which will endure 
the heat of a furnace, is highly valuable to manufacturers of 
porcelain. The ancients are supposed to have used this oxide, 
mixed with oil in their painting ; and this is given as a reason 
for the blue drapery and skies, in some old pictures being so 
durable. 

555. Sympathetic Ink may be made by digesting the oxide of cobalt iti 
hydro-chloric acid, and diluting with water. Words written with this so- 
lution of hydro-chlorate of cobalt will be invisible till brought near the fire, 
when the writing will appear of a bright green tint. The acetate and ni- 
trate of cobalt will present a blue color on being warmed. 

Let a paper fire-screen (Fig. 98,) 
represent a landscape where the 
trunks and leafless branches are 
sketched in Indian ink, and paint the 
foliage and fore-grounds with the 
hydro-chlorate, and the sky and dis- 
tant mountains with the acetate or 
nitrate of cobalt ; while the picture 
is cold, it represents merely the out- 
line of a landscape, or a winter scene, 
as at a ; on bringing it near the fire, 
(it will be transformed to a summer 
landscape, with green trees and a 
clear blue sky, as at b. On being removed from the fire, the scene will 
gradually lose its verdure, and resume its winter dress. 

The cobalt of commerce was at first wholly furnished by Sax- 
ony. The ores of this metal are now found abundantly in Swe- 
den, in a mine in Cornwall in England, and in a various parts 
of America. In Franconia, in New Hampshire, cobalt is found 

555. Sympathetic ink. Localities of cobalt. 

18* 




210 TIN. 

in arsenical iron ore; and in Chatnam, Connecticut, associated 
with nickel. It has been found in many specimens of aerolites 
or meteoric stones. 

556. Tin. — Equiv. 58. This appears to have been among 
the few metals known in the first periods of history. It is named 
by Moses in connexion with " gold, silver, brass, iron, lead, and 
every thing that may abide the fire." The Phoenicians obtained 
it in commerce, passing in their wonderful voyages the pillars 
of Hercules,* and visting Britain, the Ultima Thule f of that 
period. The most ancient and extensive tin mines are in Corn- 
wall in England. It is found in primitive mountains, in Saxony, 
Siberia, France, and Mexico. 

The alchemists, who often divided their attention between the mysteries 
of astrology and alchemy, considering that there were some secret sympa- 
thies between the planets and the metals, named tin, Jupiter, because like 
that planet it had a brilliant appearance. It was called also by the Latin 
name, stannum. 

557. Tin Plate, in which form this metal is used for a variety 
of purposes, consists of sheets of iron coated with tin. Tin Foil 
is made from the finest tin, beaten out with a hammer. Tin is 
a white, brilliant metal, with a silvery lustre. It is neither very 
hard nor ductile and has, little tenacity. It is flexible, and in 
bending gives a peculiar crackling sound. It is among the most 
fusible of the metals ; it is vaporized by the heat of the com- 
pound blow pipe. It is so soft as to be cut with a knife, or 
scratched with a pin. Its odor and taste are peculiar ; it tar- 
nishes on exposure to the air. If steam be passed over tin heat- 
ed to redness, it decomposes the water and combines with the 
oxygen, while the hydrogen gas is disengaged. 

558. Tin and Oxygen. The protoxide of tin is obtained when tin is kept 
for some time melted in an open vessel, or in contact with the air ; oxygen 
is absorbed and the product is a gray powder. The Protoxide has such an 
affinity for oxygen, that when heated to redness in open vessels it unites 
with another proportion, and becomes the peroxide. The latter is of a straw 
yellow color; and exhibits the character of an acid capable of uniting with 
potash and other alkalies. It has been called by Berzelius stannic acid, and 
we have therefore classed tin among those metals which form acids with 
oxygen. 

559. Tin combines with sulphur, forming a blueish and metallic proto-sul- 
phuret, and a beautiful gold-colored bi-sulphuret, which is used to give a 
golden color to bronze, and japanned articles, and to excite electrical ma- 
chines. Nitric acid oxidizes but does not dissolve tin. The nitro-muriatic 

* Straits of Gibralter. f The remotest land. 

556. Ancient use of tin ; its localities. Names. 

557. Tin Plate. Tin Foil. Properties of tin. Combination with oxy- 
gen. 

558. Compounds formed by tin with oxygen. 

559. The combinations of tin. Alloys. 



METALS. 211 

acid dissolves it with effervescence, forming a salt called the per -muriate of 
tin, which is employed in dyeing, especially to change the color of cochineal 
from crimson to a bright scarlet. The proto-chloride of tin is prepared by 
boiling tin filings in hydro-chloric acid. It is much used as a deoxidizing 
substance, especially for precipitating metals from their solutions. The bi- 
chloride, formerly called the fuming liquor of Libavius, is a volatile liquid, 
which emits copious white fumes. It inflames the oil of turpentine ; and 
has a strong attraction for water, which changes it to the per muriate. The 
bi-chloride may be formed by heating metallic tin in an atmosphere of chlo- 
rine; it contains two equivalents of chlorine, united to one of the metal. 

Mloys of Tin. The alloys of tin with copper in different proportions form 
bronze, bell metal, and a beautiful white substance used for the reflectors 
of telescopes. 



CHAPTER XXII. 

METALS OF THE SECOND CLASS. 

Alkaline metals, or those whose oxides are fixed alkalies, or alka- 
line earths. — Order 1, Metals which, with oxygen, form the 
fixed alkalies. 

560. The metals of this class, from their apparent doubtfuj 
character, were at first called metalloids.* They differ from 
copper, lead, gold, &c, and other well known metals in their 
less specific gravity, some being lighter than water. In their 
metallic lustre, and in uniting with oxygen to form oxides 
which, in their turn form salts with acids, they exhibit distin- 
guishing properties of metals. 

Order 1. — Metals, which, with oxygen, form the fixed alkalies, 
as potassium, sodium and lithium. 

561. The metals of this order have so great an attraction for 
oxygen, that they decompose water at the moment of contact j 
the resulting oxides are distinguished by being soluble in water, 
are hot, and biting to the taste, change vegetable blue colors 
green, and yellow colors brown, and have a caustic action on 
animal substances. They are called alkalies, and their metallic 
"bases are called alkaline metals. 

Ammonia is an alkali, but its base is not a metal, like the bases of po- 

* The Greek termination is from eidos, similar to ; the term metalloids 
signifies similar to metals. 

560. Why were the metals of this class called metalloids ? Order 1. 
Order 2. 

561. Attraction of these metals for oxygen. General properties of the 
oxides of these metals. What alkali has not a metallic base 1 



212 POTASSIUM. 

tassa, and soda ; it being a compound of nitrogen and hydrogen. Sir Hum- 
phrey Davy, after having discovered potassium and sodium, in two of the 
alkalies, was induced to make a series of experiments upon ammonia, with 
the expectation of discovering a metallic base, ammonium. But instead of 
this the decomposition of ammonia resulted in the disengagement of the two 
non-metallic elements, hydrogen and nitrogen. 

562. Potassium. — Equiv. 40. This metal is obtained by the 
decomposition of potassa, (or potash,) which was, formerly, 
considered as a pure alkali, but is now known as the oxide of 
potassium. Sir Humphrey Davy, about the year 1807, became 
deeply interested in experiments on voltaic electricity ; having 
first observed its power in separating the elements of bodies 
known to be compound, he was led to examine its effects on 
potash and soda, until that time ranked among undecomposable 
elements. His first attempts on those alkalies, were made upon 
their aqueous solutions,* but the water only was decomposed. 
He then caused a thin piece of pure hydrate of potassa, to com- 
municate with the opposite poles of a powerful voltaic appara- 
tus. The potassa soon became fused ; oxygen gas was evolved 
at the positive pole, and small metallic globules appeared at the 
surface connected with the negative pole. 

The active and comprehensive mind of Davy, on witnessing 
the success of the experiment, anticipated the great changes 
which his discovery was destined to produce in chemical 
science. Possessing the rare combination of ardent enthusiasm 
with cool philosophical research, he must have contemplated the 
victory of his genius with peculiar emotions. He foresaw that 
the elevation of his fame must be commensurate with that im- 
mortal science, the boundaries of which his labors have done so 
much to enlarge. 

563. The discovery of potassium, by Davy, stimulated tht French Chem- 
ists to new efforts, and Gay Lussac and Thenard, in 1810, succeeded in ob- 
taining the metal, without the aid of electricity, and in greater quantities 
than Davy had done. Their process consists in bringing fused hydrate of 
potassa, in contact with iron turnings, heated to whiteness in a curved 
gun-barrel. The iron attracts the oxygen from the alkali, and its metallic 
base is disengaged. 

The curved gun-barrel is represented at tf, 6, and/; (Fig. 99,) the iron 
turnings are placed within, between /, and b, which part is covered with a 
lute of infusible clay, made of five parts of sand, and one of potter's clay. 
Between a and b, are placed pieces of solid hydrate of potassa. A tube of 
safety is to be luted to the end, a, and immersed in mereury in the glass 
vessel, m. To the smaller end of the barrel, is fitted a piece of copper 
tube, and to this, a small copper receiver h, which is to receive the potas- 
sium. A tube of safety, i, communicating with this receiver, dips into 

562. What substance contains potassium ? History of the discovery ot 
the metallic bases of potassa and soda by Davy. 

563. Process discovered by Gay Lussac and Thenard, for obtaining po. 
tassium without the aid of electricity. 



POTASSIUM. 



213 



mercury contained in the vessel, b. The furnace should now be heated 
until the barrel between b and/, or that portion containing the iron turn- 
ings, is of a white heat, the other parts of the barrel being kept cool by the 
application of wet cloths. The barrel having become white hot, the hydrate 
of potassa is melted by igniting charcoal contained in the moveable cage, fe, 
and will then flow down upon the ignited iron turnings, hydrogen gas which 
was contained in the hydrate of potash, will issue through the safety tube, 
i ; the oxygen of the potassa will combine with the iron turnings, while the 
potassium passing off in vapor, will be condensed in the copper receiver at h. 

Fig. 99. 



$$£&% 




564. Properties. Potassium (prkalium) resembles other metals 
in many properties, but differs from most of them, in being of 
a less specific gravity than water. Its affinity with oxygen is so 
great, that it cannot be preserved except immersed in some sub- 
stance, from which oxygen is excluded, such as ether, or naphtha, 
or in exhausted glass tubes, hermetically sealed. 

At 32° Fahrenheit, it is brittle, and when broken, exhibits 
through a microscope, a white, crystalline appearance. It is 
solid at the common temperature, though soft, and easily mould- 
ed with the fingers. In color and lustre, it resembles mercury ; 
its specific gravity is 0.865. It becomes fluid at 150° Fahren- 
heit, and at a red heat, sublimes in the form of a greenish vapor. 

On exposure to the air, it tarnishes, becomes of a bluish color, 
and changes into the protoxide of potassium. When heated with 
oxygen gas, it burns with intense light and heat ; exhibiting a 
rose colored flame, and forming, by its combination with oxy- 
gen, the deutoxide of potassium. When thrown upon water, 
potassium acts with great violence, swimming on its surface, 
and burning with great splendor j hydrogen, is evolved and ox- 



564. Resemblance of potassium to other metals ; its difference in one 
particular. Why potassium cannot be kept in the open air. Properties. 
Effects of exposure to the air. Of burning in oxygen gas. Action with 
water. 



214 



POTASSIUM. 



ide of potassium or potassa, is found in solution. If ice be used 
instead of water, it burns with equal force. This effect is 
owing to its rapid absorption of oxygen, from which so much 
caloric is disengaged, that the hydrogen gas, resulting from the 
decomposition of water, is inflamed. 

565. Protoxide of potassium, or potassa, is commonly known by 
the name of potash, from the pots or vessels in which it was made. 
It was at first called kali, and vegetable alkali, on account of its 
being procured from the lixiviation of vegetable ashes ; but it is 
now known to exist in earths, and mineral combinations, from 
which it is imbibed by plants. 

The potash of commerce, is chiefly obtained by evaporating the ley of 
wood, or vegetable ashes. Plants of a soft texture arje found to yield more 
of the saline matter, than those with woody fibre. Resinous wood affords 
little alkali ; for which reason, the ashes of pine wood are little valued in 
families for soap-making. Potassa is a white solid substance, highly alka- 
line, and of a greater specific gravity than potassium. It has so great an 
affinity for water, that it readily absorbs it from the air, forming with it the 
hydrate of potassa, composed of 1 equivalent of potassa, and 1 of water. 

566. The peroxide of potassium is formed when potassium 
burns in the open air, or in oxygen gas. It is yellowish green, 
and gives the alkaline tests with vegetable colors. It was dis- 
covered by Gay Lussac and Thenard. 

Fig. 100. The hydrate of potash, or caustic potash, is the perox- 

ide of potassium, combined with 1 equivalent of water; 
and such is the affinity between them, that the water 
cannot wholly be expelled by the most intense heat. It 
is a white, solid mass, which fuses at a red heat, disen- 
gaging caustic, alkaline vapors. This substance is often 
cast into sticks for the use of surgeons, who employ it as 
a caustic. Pure hydrate of potassa is obtained by boiling 
a solution of potash or pearlash with quick lime. This 
solution is then to be filtered through a funnel, the threat 
of which is covered with folds of linen; but since potash 
absords carbonic acid rapidly, when exposed to the at- 
mosphere, Mr. Donovan invented the filtering apparatus 
here represented, (Fig. 100.) 

A is the filtering funnel, having its throat obstructed 
by a fold of linen to serve as a strainer ; the solution be- 
ing poured in through the mouth at b, the funnel is closed 
by a cork fitted to the tube, c, and connected at a, with 
the receiving vessel, D. The filtration will now proceed 
at the slow rate which the nature of the operation re- 
quires, and without exposure to any more air than was contained in the 
vessels at the beginning. 

567. Potassium inflames spontaneously in chlorine gas, and burns with 

565. Synonymes of the protoxide of potassium. Potash of commerce, how 
obtained ? Different proportions of potash in plants. Properties of potash. 

566. Peroxide of potassium. Hydrate of potassa. Mode of obtaining 
pure hydrate of potassa. Donovan's filtering apparatus. 

567. Combinations of potassium with chlorine, iodine, bromine, &c. 




SODIUM. 215 

great brilliancy, forming chloride of potassium. This chloride is also formed 
when potassium is heated in hydrochloric acid gas, hydrogen being at the 
same time evolved. Potassium has a stronger affinity for chlorine than for 
oxyuen, as its oxides are decomposed by chlorine gas. 

Iodide of potassium is formed, with an emission of light, when the two 
elements are heated in contact. There is a Bromide of potassium formed by 
saturating hydrate of potassa with bromine. 

Hydrogen and potassium nnite in two proportions, forming in the one case, 
a gray solid hydruret, and in the other, a gaseous hydruret, destitute of 
color. Thenard states, that when potassium is heated in ammoniacal gas, 
the hydrogen of ammonia is disengaged, and the potassium unites with the 
nitrogen, forming nitruret of potassium. The sulphuret of potassium is 
readily formed by the combination of the two elements by means of heat. 
It has a red color, and is very fusible- 

Potassium unites with phosphorus, forming a phosphurct. It also com- 
bines with cyanogen, forming a cyanide or cyanuret of potassium. 

568. Sodium. — Equiv. 24. This metal in many of its proper- 
ties resembles potassium. And was discovered by Sir H. Davy, 
soon after his discovery of potassium. It may be obtained by the 
same electrical and chemical processes, with pure hydrate of 
soda ; but requires, in its decomposition, a stronger voltaic 
power, and a higher degree of heat. 

Properties. It is brilliant like silver, when kept from the air ; 
is solid at the common temperature, soft and ductile like wax. 
It is somewhat heavier than potassium, its specific gravity at 59° 
Fahrenheit, being 0.972. It therefore nearly floats on water. 
It is less fusible than potassium ; becomes fluid at about 190° 
Fahr., but does not vaporize, except at a very high temperature. 
Its attraction for oxygen is less energetic than that of potassium. 
Its combustion with this gas does not take place till near igni- 
tion ; it then burns with a yellow flame, and bright scintillations, 
producing a yellow compound, which is a mixture of the pro- 
toxide and deutoxide of sodium. It fuses on cold water, with a 
hissing noise, appearing like a globule of silver, and gradually 
melting away ; but without emitting light. On hot water, there 
is an appearance of sparks and flame. In this combustion, the 
sodium unites with the oxygen, forming soda. Sodium tarnish- 
es on exposure to the air, in consequence of its attraction for 
oxygen ; and like potassium, should be preserved in some sub- 
stance in which it is insoluble, and which is free from oxygen. 

569. The protoxide of sodium, or soda, is obtained by burning 
sodium in dry atmospheric air, or when sodium is oxidized by 
burning on water. It is solid, white, caustic, turns to green 
vegetable blue colors, deliquesces by attracting carbonic acid 
from the air, and becomes efflorescent. It exists in nature, only 

568. Analogies of sodium and potassium. Properties. Attraction for 
oxygen. Combustion in oxygen. Action with water. Effect of air on so- 
dium. 



216 SODIUM. 

in combination with acids, and some metallic oxide. Like the 
protoxide of potassium, its affinity for water is such, that, at 
the highest temperature, it always retains a certain quantity j 
and can only be obtained in the state of a hydrate, or with 1 
equivalent of water. 

The peroxide of sodium, is obtained by heating sodium to red- 
ness in an excess of pure oxygen. It is an orange colored sub- 
stance. It is resolved by water, into oxygen and sodium, and 
loses part of its oxygen by heat. 

"Soda, (or rather the hydrate of soda,) is distinguished from 
other alkaline bases, by the following characters. 1st. It yields 
with sulphuric acid, a salt, which, by its taste and form, is 
easily recognized as Glauber's salt, or sulphate of soda. 2nd. 
All its salts are soluble in water, and are not precipitated by 
any re-agent. 3d. On exposing its salts by means of platinum 
wire to the blow pipe flame, they communicate to it a rich 
yellow." Turner. 

570. Chloride of Sodium. This union of sodium and chlorine 
is the compound so well known in all countries, as common salt. 
This substance, which exists extensively in nature in a solid 
form, as in rock salt, and in solution in salt springs and sea-wa- 
ter, was formerly called muriate of soda, being regarded as a 
compound of muriatic acid and soda. But as it may be formed 
by the direct combination of sodium and chlorine, it is evident 
that it is a binary compound consisting of a metallic base and a 
simple non-metallic element. When sodium is burned in 
chlorine gas the result of the combustion is chloride of sodium. 

It may also be formed by heating sodium in hydro-chloric pas, the chlorine 
unites with sodium and hydrogen is liberated. Sea-water is a hydro-chlo- 
rate of soda, but by evaporation becomes chloride of sodium ; for hydro- 
chlorates are changed into chlorides by heat, or by evaporation. Hydro- 
chlorate of soda, for example, consists of hydro-chloric acid and soda, (oxide 
of sodium,) the hydro-chloric acid gives off its hydrogen, and the soda ils 
oxygen ; these uniting form water, which passes off by evaporation, while 
the chlorine is left in combination with sodium. The hydro-chlorate of 
potassium, in the same manner, forms chloride of potassium. The chloride 
of metals are changed into hydro-chlorates by the decomposition of water; 
the hydrogen of the water uniting with the chlorine of the chloride forms 
hydro-chloric acid ; and the oxygen of the water forms with the metal an 
oxide, and again the combination of the hydro-chloric acid with this oxide 
constitutes a salt called a muriate, or hydro-chlorate. 

571. Properties. The chloride of sodium (common salt) is 

569. Protoxide, how obtained ? Properties. Peroxide. How is soda 
distinguished from other alkaline bases ? 

570. Composition of chloride of sodium. Synonymes. How proved to 
be a binary compound ? How produced. How does sea-water become 
chloride of sodium ? Chlorides of metals changed into muriates. 

571. Properties of chloride of sodium. 



LITHIUM. 217 

transparent and colorless : it crystalizes in cubes. Its taste, 
though used as a standard of comparison for saline bodies, can- 
not be defined, except negatively, that is, it is not sour, bitter, 
sweet, metallic, or astringent. It is grateful and agreeable j it 
decrepitates at red-heat, and suffers igneous fusion without 
being decomposed. By an increased heat, it vaporizes in a 
white smoke, which condenses in the cold. It is remarkable 
for being equally soluble in cold, as in hot water ; it is al- 
most insoluble in alcohol. In the arts, salt is often used to in- 
crease the intensity of fire ; this it does by accumlating and 
transmitting heat to the surrounding combustibles. It gives 
to flame a yellowish tinge. 

572. Chloride of soda (chloride of oxide of sodium), is formed when chlorine 
gas is passed through a solution of soda or its carbonate. "It emits an odor 
of chlorine, and possesses the bleaching properties of that substance in a 
high degree. When kept in open vessels it is slowly decomposed by the 
carbonic acid of the atmosphere with evolution of chlorine ; and the change 
is more rapid in air charged with putrid effluvia ; because the carbonic 
acid produced during putrefaction, promotes the decomposition, of the chlo- 
ride. On this depends the efficacy of this chloride in purifying air loaded 
with putrescent exhalations. Chloride of soda may be employed in bleach- 
ing and for all purposes, to which chlorine gas, or its solutions, was for- 
merly applied." — Turner. 

573. Sodium unites with iodine and bromine ; and among the 
combustible bodies, with sulphur, phosphorus and selenium. It 
forms alloys with many of the metals. Its salts are numerous 
and important. 

Silliman remarks, '* the great prerogative of sodium is to attract oxygen, 
in which function it is only inferior to potassium. Both these remarkable 
bodies are endowed with such a degree of activity, and their chemical re- 
lations are so numerous, as almost to realize the brilliant suggestion of 
their illustrious discoverer, that they approach to the character of the im- 
aginary alkahest of the ancient alchemists. Nothing can be more unex- 
pected than that common salt and sea weed should contain each a metal, 
oi wood ashes another. In the present state of our knowledge we must 
regard potassium and sodium as elements. As they exist abundantly in 
minerals, we can understand how in the processes of vegetable life, they 
should become constituent parts of plants." 

574. Lithium. — Equiv. 10. This mineral is the base of a new 
alkali called lithia, discovered in 1818, by M. Arfwedson, then 
a young student in the laboratory of Berzelius. Its name is 
from the Greek, lithos, a stone. It has hitherto only been found 
in minerals, as the petalite, spodumene, tourmaline, in some va- 
rieties of mica, and in certain waters of Bohemia. 

572. Chloride of soda. 

573. Combinations of sodium with other simple elements, ice. Silliman's 
remarks. 

574. Discovery of lithium. Derivation of the name. Where found. 

19 



218 SECOND CLASS OF METALS. 

575. Lithia or oxide of lithium is obtained by a complicated process* from 
its mineral combinations. It is a white, caustic substance, changing ve- 
getable blue colors green, and is in most respects, analogous to soda and 
potassa. Its tendency to act upon platinum is such, that, according to 
Berzelius, that metal can always be depended on to detect the presence of 
lithia in any mineral. 

576. Sir Humphrey Davy succeeded in decomposing lithia by galvanism ; 
but the metallic base was so rapidly oxidized, and thus reconverted into 
alkali, that it could not be collected. The pure metal was, however, ob- 
served sufficiently to show it to be of a silvery whiteness like sodium, and 
it burned with bright scintillations. 

Lithia is distinguished from potassa and soda by its power of saturating 
a greater quantity of any acid. The chloride of lithium dissolves in alcohol, 
and the solution burns with a red flame. " The salts of lithia when heated 
on platinum wire before the blow-pipe tinge the flame of a red color." — 
Turner. 



CHAPTER XXIII. 

SECOND CLASS OF METALS. 

Order II. Metals which, with oxygen, form alkaline Earths. Ba- 
rium, Strontium, Calcium, and Magnesium. 

577. Difference between the alkaline earths and the fixed alka- 
lies. They are less soluble in water, less fusible and not 
volatile by any heat hitherto applied. Resemblance. In common 
with the fixed alkalies, the alkaline earths are acid and caustic, 
give the alkaline test with vegetable colors, form soap with oils, 
and combine with acids to form salts. They belong to a natural 
class of bodies called by the general name of earths, and which, 
until recent discoveries, were supposed to be simple elements. 

578. Barium. — Equiv. 70. This metal is little known. It 
was obtained by Sir H. Davy, in 1808. It is of an iron gray 
color, with little lustre ; it is heavier than water, its specific 
gravity being 4. It attracts oxygen from the atmosphere and 

* See Dictionary of chem. art. oxide of Lithium. 

575. Lithia. Its properties. 

576. Lithium obtained by Davy. Properties. Lithia distinguished from 
potassa and soda. Chloride of lithium. Colored flame of the salts of lithia. 

577. How do the oxides of the metals of the 2nd. order differ from those 
of the 1st. order? What resemblance between them? 

578. Discoverer of barium. Properties. Attraction for oxygen. How 
is baryta obtained ? Its absorption of oxygen. Properties of baryta. Hy- 
drate of baryta. Crystals of the hydrate of baryta. Test furnished by so- 
lution of baryta. 



STRONTIUM. 219 

from water, and, crumbles into a white powder, which is the 
-protoxide of barium. 

The protoxide of barium, commonly called barytes or baryta, 
was so named from the Greek, barus, ponderous, on account of 
its great specific gravity. It was discovered by Scheele in 
1774. Baryta is obtained by the decomposition of the carbonate 
of baryta, effected by means of heat. It is the sole product of 
the oxidation of barium in air, or water. When heated with 
oxygen gas, it absorbs it and becomes the deutoxide of barium. 
Baryta is a gray powder, possessing alkaline properties as dis- 
tinct as those of potash and soda, except that it is less caustic 
and less soluble in water. It has a great affinity for water. 
When mixed with that liquid it slakes in the same manner as 
quick lime, with the production of more intense heat, and even 
light is said to be sometimes, evolved. The result of this pro- 
cess is a hydrate of baryta, consisting of one equivalent of baryta 
78, and one of water 9, making its combining equivalent 87. 
The aqueous solution of baryta furnishes a valuable test of the 
presence of carbonic acid, in the atmosphere, or in other gaseous 
mixtures. The carbonic acid unites with the baryta, and a 
white insoluble carbonate of baryta is precipitated. 

579. Peroxide of barium, may be obtained by heating baryta, (the protox- 
ide of barium,) in oxygen gas. The peroxide is of a greenish gray color, 
possessing most of the alkaline properties. Exposed to heat, it loses a por- 
tion of oxygen and becomes a. protoxide. 

All the soluble salts of baryta are poisonous. The carbonate, which dis- 
solves in the juices of the stomach, acts on the system as a poison. 

The sulphate of barium is inert, being perfectly insoluble. 

Barium forms with different elements, a chloride, iodide, bromide, fluoride, 
aulphuret, cyanuret, sulpho-cyanuret, and phosphuret. 

580. Strontium. — Equiv. 44. This is the metallic base of 
strontia, an earth so similar to baryta, as to have been considered 
the same until about 1791, when Dr. Hope, of Edinburgh, ex- 
tracted what he considered as a new earth, from strontianite, a 
mineral found in the lead mine at Strontian in Scotland. It resem- 
bles barium in being very ponderous and in general appearance. 
Sir H. Davy obtained the metallic base, Strontium, by a process 
analogous to that by which he evolved potassium from potassa. 

581. The protoxide of strontium, (or strontia,) exists in nature, 
only in combination with carbonic and sulphuric acids. It may 
be obtained by the decomposition of the native carbonate of 

579. Peroxide of barium. Salts of baryta. Chloride, &c. 

580. Of what is strontium the base? "What does it resemble? Disco- 
very. &e. 

581. Protoxide. Peroxide. How found in nature ? How obtained? Hy- 
drate of strontia. Colored flame of strontia. Peroxide, &c. Binary com- 
pounds. Salts of strontia. 



220 CALCIUM. 

strontia, or of the prepared nitrate. When mixed with water, 
it slakes violently like baryta, and produces intense heat, form- 
ing a white powder, which is the hydrate of strontia, composed 
of one equivalent of strontia, and one of water. Strontia gives 
to the flame of burning alcohol, a blood-red color. The peroxide 
of strontium, has only been obtained in the state of a hydrate. 
It may be prepared by pouring a solution of the protoxide, or 
strontia, into oxygenated water ; the hydrated peroxide precipi- 
tates in pearly scales. 

Sulphate of strontium, is found on the shores of lake Erie, 
and in some other parts of this continent. The carbonate is 
more rare. The artificial nitrate, is used in forming the blood- 
red fire of fire-works. 

Strontium unites with chlorine, iodine, and sulphur, forming 
binary compounds. Strontia forms salts with acids, resembling 
the salts of baryta. 

5S2. Calcium. — Equiv. 20. This metal does not exist pure, 
in a native state. Its oxide, lime is very abundant. Calcium 
is of a silvery whiteness, heavier than water, and solid at the 
common temperature ; its affinity for oxygen is so great that it 
absorbs it from most other bodies, and oxidates, or becomes 
lime in contact with air, or water. The existence of a metallic 
base in lime, had been suggested by Berzelius, before its actual 
discovery by Davy. When lime is subjected to the action of 
the galvanic battery, oxygen is evolved at the positive pole and, 
calcium appears at the negative pole. The quantities of this 
metal hitherto obtained, have been too small to afford an oppor- 
tunity for the study of its properties.* 

583. The protoxide of calcium, or lime, is extensively diffused in nature ; 
it constitutes a part of the teeth and bones of animals, exists in many vege- 
table combinations, and forms a large portion of the rocky strata of the 
earth. It was formerly called calcareous earth. In Latin, it was called 
calx, a word supposed to be derived from the Arabian kalah, to burn, from 
which comes calcine ; thus, a burnt mineral, is said to be calcined. 

Lime is not found pure in nature; but is obtained by calcination of car- 
bonate of lime, which exists in various forms, as limestone, chalk, marble, 
&.c. For purposes of commerce, lime is obtained sufficiently pure, by cal- 
cining the common limestone in lime kilns. For use in the laboratory, 

* Dr. Hare in 1839 was engaged in attempts to obtain calcium, when he 
exhibited to the author, with much exultation a few small silvery grains of 
the metal not much larger than a pin's head, which he had just obtained 
by decomposing lime. 

582. Calcium. Properties. Existence of the metallic base of lime sug- 
gested by Berzelius. How obtained ? 

583. Protoxide of calcium, its composition. Its existence in nature. 
Meaning of the terms calcareous, and calcine. Modes of obtaining lime. 
Calcined lime. Its properties. Promotes the fusion of other bodies. 



CALCIUM. 221 

powdered white marble, chalk, or shells are heated in a covered crucible ; 
the carbonic acid is expelled, and pure lime remains. When fully calcined, 
lime will not effervesce with acids. In its pure state, it is called quick lime. 
It is a white earthy solid, having an astringent, and alkaline taste, and 
giving the alkaline test with vegetable colors. When moist, it corrodes 
animal substances. Its specific gravity is 2.3. Though very infusible, it 
melts before the galvanic current. Notwithstanding its infusible nature, it 
is remarkable for promoting the fusion of other mineral bodies, and, there- 
fore, is employed in the reduction of metals. 

584. Lime has a great affinity for water, which when added to it, pro- 
duces intense heat; the water, in solidifying, sets free a large portion of 
caloric, and unites with the lime, forming a hydrate of lime. 

This appears in the form of a white, bulky powder, consisting of 1 equiv- 
alent of lime, 28, with 1 of water, 9, making its equivalent number 37. 
This well known process is called slaking, or slacking lime, and the hydrate 
is called slaked or slacked lime. This hydrate requires a large proportion 
of water to dissolve it, as may often have been noticed by those who pre- 
pare lime for white-washing walls, brick-layer's mortar, &c ; and it is a 
singular fact, that, for this purpose, it requires more hot, than cold water ; 
thus, on heating a cold solution of lime-water, lime is precipitated. A hy- 
drate of lime is formed when quick lime is exposed to the air ; it gradually 
crumbles to powder, as the hydrating process goes on. This air slaking 
changes the peculiar properties of lime, while the mere water slaking does 
not ; this is because the lime, in absorbing moisture from the air, also ac- 
quires carbonic, acid, and then becomes carbonate of lime, which is insolu- 
ble, and effervesces with acids. 

Lime-water is a solution of the hydrate made by mixing with 
it, a large proportion of water ; its taste is acrid, and it gives 
the alkaline test with vegetable colors. It is not caustic, and 
is a valuable medicine. It absorbs carbonic acid from the at- 
mosphere, and should be kept in well stopped bottles. 

Mixed with sweet oil, it forms an excellent liniment for 
burns. 

The milk of lime, is made by mixing with the hydrate, merely sufficient 
water to give it a liquid form, of the consistence of a thin paste. It is used 
for the purpose of purifying gases from carbonic acid gas ; by causing them 
to pass through this preparation, the carbonic acid gas is absorbed by the 
lime. The simple lime water is used for the same purpose, though from 
having less of the earth in solution, it is less effective. Crystals of hydrate 
of lime may be obtained by placing lime-water under the exhausted receiver 
of an air pump, with sulphuric acid in another vessel. The acid having 
the property of absorbing watery vapor, facilitates the process of evapora- 
tion. 

585. The peroxide or deutoxide of calcium may be formed by 
passing oxygen gas over ignited lime. 

Chloride of Calcium. The metal calcium is too rare to be 

584. Hydrate of lime, or slacked lime. Action of air upon quick lime. 
Lime water. Milk of lime. Crystals of hydrate of lime. 

585. Peroxide of Calcium. How is the chloride of calcium formed ? 
What change takes place when this chloride is dissolved in water ? Chlo- 
ride of lime. How prepared ? How does it act as a disinfecting agent ? 
Is it a definite compound ? 

19* 



222 CALCIUM. 

united directly with chlorine, to form the chloride ; but when 
pure lime, (protoxide of calcium,) is heated in chlorine, the 
latter unites with calcium, and oxygen is disengaged. When 
dissolved in water, it forms, by a new arrangement of elements, 
the hydrochlorate of lime. This forms, with snow, one of the 
most powerful freezing mixtures. It is valuable for medicinal 
purposes ; and may be easily prepared by dissolving powdered 
marble in hydrochloric acid. 

Chloride of Lime (chloride of the oxide of calcium) is the combination of 
chlorine with lime. It possesses the bleaching, and other important proper- 
ties of chlorine, and is, in many respects analogous to chloride of soda, (see 
§ 572.) It was formerly called oxymuriate of lime, or bleaching powder. 
It is prepared by exposing newly slaked powdered lime to an atmosphere of 
chlorine gas. The chlorine combines with lime, forming a dry white pow- 
der, having a smell of chlorine, and a strong taste. Its watery solution ex- 
posed to the air, gradually disengages chlorine, and thus acts as a disinfect 
ing agent. It is doubtful whether chloride of lime is a definite compound ; 
— according to Dr. Hare, its elements do not constitute a regular atomic 
combination. 

586. Fluoride of calcium according to theory, is composed of 
1 equivalent of calcium, 20, and 1 of fluorine, 10. It is found 
native, and constitutes the beautiful mineral called jiuor spar, 
which is sometimes manufactured into ornamental vases. Its 
usual color is that of a rich purple, but by exposing it to differ- 
ent degrees of temperature, artists have found means of forming 
it into a variety of beautiful colors. The finest varieties are 
obtained from the Derbyshire mines in England. The term 
fluor, was given to this mineral, because, being fusible, it is 
used as a flux for ores. 

587. We have before remarked, (see § 298,) that the subject of fluorine 
and its compounds, is involved in obscurity. Since fluorine has never yet 
been obtained in a separate state, there can be no synthetic proof, (or proof 
by a direct combination of the two elements,) of the existence of a fluoride 
of calcium, as there is by the union of chlorine and sodium, of a chloride of 
sodium. The existence of the fluoride of calcium is only inferred by analogy. 
When fluor spar is decomposed by hydro-sulphuric acid, the result is analo- 
gous to that obtained by the decomposition of common salt, or chloride of 
sodium. It is supposed that, the hydrogen of the water in the sulphuric 
acid, uniting with fluorine of the fluoride, forms hydro-fluoric acid in the 
one case, and with the chlorine of the chloride in the other, forms hydro- 
chloric acid ; while the oxygen of the water, uniting with the disengaged 
calcium, and sodium forms lime and soda; these newly formed alkalies, 
combining with the sulphuric acid, the result is, in the one case, a solid 
pulphate of lime, and in the other, a solution of sulphate of soda. The af- 

586. Fluoride of calcium, composition, from what mineral obtained, &c. 

587. The existence of this fluoride inferred by analogy. Decomposition 
of fluorspar by hydro-sulphuric acid. Apparent analogies in the decompo 
sitiop of fluor-spar and common salt, by sulphuric acid and water. Arti- 
ficial fluor-spar. Combination of calcium with iodine, &c. Salts of lime. 
Their uses. 



MAGNESIUM. 223 

finities which determine the change, are the attraction of fluorine and 
chlorine for hydrogen, of calcium and sodium, for oxygen and of lime and 
soda, for sulphuric acid. 

If lime, (oxide of calcium,) be added to hydro-fluoric acid, much heat en- 
sues, the hydrogen of the acid forms water with the oxygen of the lime, and 
the fluorine and calcium uniting, form the same substance as fluor spar, or 
fluoride of calcium. This compound may be obtained by digesting newly 
precipitate carbonate of lime, in an excess of hydro-fluoric acid. 

The iodide, bromide, sulphuret, and phosphuret of calcium, have been 
little studied, and their properties are but imperfectly known. 

The salts of lime, as the sulphate, carbonate, &c, constitute a large por- 
tion of the minerals of the globe, and enter into the composition of vegeta- 
ble and animal substances. Few substances are of more general utility 
than lime; it is used in medicinal preparations; in the laboratory as an 
important re-agent; in soap-making, to disengage carbonic acid from potash 
and soda ; in agriculture, in building, and in various other arts and manu- 
factures. 

588. Magnesium. — Equiv. 12. Sir H. Davy failed in his at- 
tempts to procure this metal from magnesia, by galvanic power; 
but succeeded better by subjecting solutions of the sulphate and 
nitrate of magnesia, to the action of the voltaic battery. It 
has since been obtained by the action of potassium on chlo- 
ride of magnesium, heated to redness in a tube of porcelain. 
It has a brilliant silvery lustre ; when heated intensely, it burns 
with a vivid light, and unites with oxygen, forming a white 
oxide, or the powder called magnesia. When thrown into 
water, it gradually changes into the same white oxide. 

589. The oxide of magnesium, or magnesia, exists in combina- 
tion with acids, extensively, in the mineral kingdom, forming 
a component part of talc, soap-stone, serpentine, and asbestos. It 
exists in sea water, and in many mineral springs. 

Magnesia may be obtained pure by heating the carbonate of magnesia, 
and thus expelling the carbonic acid. The product is called calcined mag- 
nesia ; this, in most cases, is preferable as a medicine, to the carbonate, be- 
cause no gas is generated by it in the stomach. 

Properties. Magnesia is a white, earthy powder, having neither 
taste nor odor. It gives the alkaline test with vegetable colors, 
though less strongly than the other alkaline earths. It has the 
essential character of alkalinity, that of forming neutral salts 
with acids. It absorbs water, and carbonic acid from the atmo- 
sphere. It is a mild, harmless substance, very infusible, and 



588. How has magnesium been obtained ? Properties of this metal. 

589. Oxide of magnesia, &c. How obtained pure? Calcined magnesia, 
Properties of magnesia. Its alkaline properties, &c. Hydrate of magnesia. 
Its sulphate soluble. Infusible nature of magnesia. What substance pro- 
motes its fusion ? Magnesian clays useful in porcelain manufacture. Chlo- 
ride of magnesium. Chloride of magnesia. Remarks on the division of the 
metals founded on the nature of their oxides. 



224< ALUMINUM. 

insoluble. Minerals which contain a large portion of magnesia, 
are infusible, as soap-stone, which is used in furnaces. 

Chloride of magnesium is obtained by passing chlorine gas over magnesia 
heated to redness ; in which process, oxygen gas is evolved. A chloride of 
magnesia is prepared by mixing a solution of chloride of lime, and sulphate 
of magnesia ; it seems to possess properties analogous to those of the chlo- 
rides of soda and lime. 

We have now completed our examination of the two orders in the second 
class of metals, including all whose oxides are either fixed alkalies, or al- 
kaline earths. The distinction which we have made with respect to the 
metals, is, perhaps, rather conventional than natural. There is a gradual 
decrease of alkalinity, from potash to magnesia, and, an equal increase of 
earthy properties ; so that it might be considered as somewhat doubtful, 
whether magnesium should be classed among metals whose oxides are a/fea- 
line earths, or pure earths. 



CHAPTER XXIV. 

THIRD CLASS OF METALS. 

Earthy Metals ; or those whose oocides are Earths. 

590. The existence of the metals of this class rests upon 
strong analogy, rather than the results of experiments. They 
exist in mature, only in the form of oxides, which are known 
by the general name of ea?*ths ; having neither the alkaline taste, 
nor giving the alkaline test with vegetable colors. 

591. Jlluminum. — Equiv 10. This is the metallic base of 
the earth alumina, (alumine of pure clay.) Sir H. Davy failed 
in his attempts to obtain this metal by galvanic power, though 
he proved that alumina was an oxidized body ; for when heated 
to whiteness, and brought into contact with the vapor of potas- 
sium, potassa was generated, which is an evidence that oxygen 
was imparted to the potassium by the body in contact. 

Dr. Wohler has succeeded in obtaining the metallic base of alumina, by 
heating a mixture of dry chloride of aluminum with potassium. On throw- 
ing the mass into water, a granular metal, resembling gun-powder falls to 
the bottom of the vessel. When the powder is rubbed on a hard substance 
with a burnisher, the particles adhere strongly, and form a surface which 
strongly reflects light, and is a conductor of electricity ; in the state of pow- 
der, it is a non-conductor. It burns with great splendor, when heated in 
oxygen gas, and with the evolution of so much heat as partially to fuse the 
alumina, which is formed, and which is one of the most infusible of all sub- 
stances. 

590. Evidence of the existence of these metals. Nature of their oxides. 

591. What is aluminum ? Davy's attempts to decompose alumina. How 
did Wohler obtain the metallic base of alumina ? Properties of the metallic 
substance obtained. 



ALUMINUM. 225 

592. Oxide of Aluminum, alumine, or pure clay, is widely dif- 
fused in nature. It is a constituent of every soil, and of almost 
every rock ; is the basis of porcelain, pottery, and bricks, and 
forms a part of fuller's earth, ochres, pipe-clay, &c. It consti- 
tutes either alone, or with other substances, in a crystaline 
form, most of the precious stones, as the topaz, sapphire, ruby, 
and garnet. Its affinity for vegetable coloring matter, is made 
use of in the preparation of lakes, for painting, and in dying 
and calico printing. Its name is from alumen, the Latin name 
of alum, of which it is the basis. It was considered as a simple 
substance, until the discovery of the alkaline metals suggested 
that it might be a metallic oxide. 

593. Pure alumine is seldom found in nature ; it may be obtained from 
alum, (sulphate of alumina and potassa,) by precipitating its solution by a 
carbonate of soda, or potassa; a white bulky hydrate of alumine is thus 
obtained, which, when washed and subjected to intense heat, becomes an- 
hydrous, leaving the pure alumine in the form of a white powder. It has 
neither taste nor smell, and has no effect on vegetable colors. It is fusible 
at a very strong heat forming a vitreous substance, so hard as to scratch 
glass. Though insoluble in water, pure alumina attracts it powerfully. 
Dr. Henry stales, that after ignition, it attracts water so fast from the air, 
that balances show the increase of weight. It is this thirst, (to use a met- 
aphorical expression,) of alumina for liquids which renders potter's clay, 
and fuller's earth so useful as absorbents of oil and grease, when carpets, 
or silken, or woollen cloths are thus soiled. The aluminous earth in pow- 
der, is laid thickly, upon the spot, and some bibulous paper, (that is, coarse 
paper without sizing, which readily imbibes moisture,) placed over the pow- 
der ; a warm flat-iron, should be set upon the paper, that the oil to be with- 
drawn, may be kept in a fluid state, and thus acted upon by the absorbent 
earth. The paper assists in the process of absorption. 

After removing once or twice the saturated earth and paper, and re- 
placing them with other, the oily matter will be found wholly extracted. 
Spanish white, or oxide of bismuth, from its possessing the same absorbing 
property, has been found almost equally useful in similar cases. 

Though alumine is insoluble in water, it forms with it a ductile, plastic, 
cohesive and infusible paste, susceptible of being moulded into regular 
forms, a property on which depends its use in the manufacture of porcelain 
and common pottery. But as alumine shrinks by heat, it is necessary that 
silica which does not possess this property, should be united with it in pot- 
tery. The natural clays often contain a sufficient portion of silica ; when 
they do not, manufacturers mix with the clay-paste, siliceous sand, or pul- 

592. Oxide of aluminum. Its existence in nature. Affinity for vegeta- 
ble coloring matter. Origin of the name alumine. When first supposed to 
be a compound body ? 

593. How may pure alumine be obtained ? Properties of pure alumine. 
Attraction for water. Absorbent properties of potter's clay and fuller's 
earth. Process for extracting oil by their agency. Property of alumine 
which renders it useful in porcelain manufacture. Why silica should be 
united with it in pottery. Use of magnesia with alumine in pottery. In 
jurious effect of a large proportion of lime. Difference in the processes o» 
glass making and pottery. Application of the contraction of clay by heat 
to the construction of a pyrometer. 



226 zirconium. 

verized flints. Magnesia which enters into the composition of clays, is, 
from its infusible nature, and from its contracting but little in the fire, a 
valuable ingredient. But if lime exists in the clay in any great proportion, 
it will injure the ware, by acting as a flux, and thus melting the vessels 
while baking them, destroying their regularity of form. Though the manu- 
factories of glass and pottery, may seem to be but branches of one art, they 
are entirely different, while glass is softened by heat, and wrought at a 
high temperature, clay is wrought when cold and afterwards hardened by 
heat. The contraction of clay by heat, is so regular according to the in- 
crease of temperature, that Wedge wood 's pyrometer, or instrument for meas- 
uring high degrees of heat, has been constructed upon this property. 
Pieces of clay of certain definite dimensions, exhibit the same amount of 
contraction, when exposed to the same degrees of heat. 

594. Pure alumine was formerly called argil, from the Latin 
argilla, pure clay ; aluminous earths, or those containing clay 
have hence been called argillaceous ; and clay slate is called 
argillite. 

595. Alumina appears to possess both the properties of an acid and an 
alkali. Of an acid, by uniting with alkaline bases, and of an alkali by unit- 
ing with acids to form salts. It is characterized by the following proper- 
ties. 1st. It is separated from acids as a hydrate, by all the alkaline car- 
bonates, and by ammonia. 2nd. It is precipitated by potassa or soda, but 
the precipitate is, commonly, rt-dissolved by an excess of the alkali. 

Chloride of Aluminum, was obtained by Prof. Oersted, some years ago, by 
a direct combination of the two elements ; by acting on this compound with 
an amalgam of potassium and mercury, and expelling the mercury by heat, 
he obtained a metallic substance which he believed to be aluminum, or the 
metallic base of alumina ; and he requested Wohler to pursue the investi- 
gation. The latter did not succeed, until he substituted pure potassium for 
the amalgam. (See § 591.) 

596. Zirconium. — Equiv. 33. In 1824, Berzelius succeeded 
in decomposing the earth, zirconia, and obtained a peculiar sub- 
stance, black, like charcoal, which neither oxidates in the air, 
water, nor in any of the acids, except hydrofltiorine, when hy- 
drogen gas is disengaged. It burns intensely when heated in 
the open air, absorbs oxygen, and becomes zirconia, or the oxide 
of zirconium. Berzelius did not consider it a metal ; it posses- 
ses some metallic lustre, but has not yet been proved to be a 
conductor of electricity. It combines with sulphur, forming a 
chestnut-brown sulphuret, like that of silicon. 

The oxide of zirconium, or zirconia is a white earth, which 
was first discovered in a mineral of Ceylon called jargoon, from 
whence came the name. This earth is now found in the 
minerals called hyacinth and zirconite. It resembles alumina in 

594. Derivation of the word argillite. 

595. Acid and alkaline properties of alumina. Two distinguishing char- 
acteristics of alumina. Chloride of aluminum. 

596. Decomposition of Zirconia by Berzelius. Properties of the sub- 
stance obtained by Berzelius by this decomposition. Oxide of Zirconium. 



THORINUM. 227 

its pure white color, insolubility with water, and in being taste- 
less and without odor. 

597. Glucinum. — Equiv. 26. It was obtained in 1758, by 
Wohler, on decomposing the chloride of glucinum, by heating 
it with potassium. The process is similar to that for obtaining 
aluminum, (see §591.) Glucinum appears in the form of a 
dark gray powder, which by polishing, acquires a metallic 
lustre, and burns in the open air with a vivid light. Oxide of 
Gluncinum, or glucina was discovered by Vauquelin in 1795 in 
the beryl, and by him considered as a simple substance, it was 
at first called berillia ; the name glucina which was afterwards 
given, it, is from the Greek, glukos, sweet, its salts having a 
sweetish taste. It is found in the beryl, emerald, and a few 
other rare minerals. Like alumine it is a soft, white powder, 
and adheres to the tongue like pure clay. 

598. Yttrium. — Equiv. 32. It is obtained from yttria, a Swe- 
dish mineral of the earthy class which was discovered by Gadolin 
in 1794, in Ytterby, and Sweden. The metal is of a grayish-black 
color and a scaly texture. The earth, yttria resembles glucina, 
but may be distinguished from it by the purple color of its sul- 
phate, and by being insoluble in potassa. 

599. Thorinum. — Equiv. 59. In 1816, Berzelius, in analyzing 
the Swedish minerals which afford yttria, supposed he had dis- 
covered a new earth, which he named thorina, from TAor, an an- 
cient Scandinavian deity. But this earth, he afterwards found to 
be the phosphate of yttria. In 1828, he received from Norway, a 
black heavy mineral, now called thorite, which, on analysis, was 
found to contain a new earth resembling the substance he had 
named thorine. On account of this analogy, and perhaps to re- 
mind the scientific world that, if he had misnamed one substance, 
he had made ample compensation by the discovery of another 
to fill the vacancy, he applied to this new mineral the exploded 
name, thorina. Thorinum, the base of thorina, is obtained in 
the same manner as the metals of the other pure earths by the 
action of potassium on its chloride. Its oxide, thorina is distin- 
guished among the earths for its snowy whiteness. A carbonate 
of thorina is formed by heating thorina with sugar, this furnish- 
es carbon, which the oxygen of the air changes to carbonic acid, 
and the latter uniting with thorina forms a carbonate. 

597. Glucinum, when obtained I Properties. Discovery of glucina. 
Names. Where found ? Properties. 

598. Discovery of yttria. Properties of yttrium and of its earthy com- 
pound, yttria. 

599. The name thorinum improperly applied by Berzelius. How is tho- 
rinum obtained ? Properties of thorina. How distinguished ? Carbonate 
of thorinum. _ 



228 METALS. 

600. The atomic weight of the metals of the third class, is yet in a de- 
gree doubtful, as are also the combining proportions of their oxides. Neith- 
er the metals, nor their oxides, can be easily obtained in sufficient quanti- 
ties for the purpose of thorough, and extensive experiments. Though alu- 
minous earth exists every where around us, pure alumine is obtained but 
by a tedious and delicate process; and its metallic base is with still more 
difficulty set free. The other pure earths, are obtained from rare minerals, 
and their separation is attended with equal difficulty as that of alumina. 



CHAPTER XXV. 

FOURTH CLASS OF METALS. 

Metals whose oxides are not regarded as acids, alkalies, or earths. 

601. In the 1st class of metals, we have found those, which, 
by combining with a large proportion of oxygen, form acids, 
thus we have arsenic acid, chromic acid, &c. In the 2d class 
we met with metals whose combinations with oxygen were alka- 
lies / as potash and soda. The 3d class exhibited metals, which, 
by combining with oxygen, form insipid earths, with neither 
acid, nor alkaline properties, as alumina, &c. In these three 
classes, the metals, with few exceptions, are little known, ex- 
cept in the laboratory of the chemist ; while their oxides, (by 
which term, in its most general sense, we mean combinations 
with oxygen, whether acid, alkaline, or earthy,) are, in general, 
familiar to all 

In the 4th class or that we are now to consider, we shall find 
metals, whose oxides are neither acids, alkalies nor earths. 
These metals have been familiar to mankind, from the earliest 
ages. From their having less affinity for oxygen, than those of 
the other three classes, they may be exposed to the air without 
oxidating. A few newly discovered metals of this class are, as 
yet, but little known. 

602. Iron. — Equiv. 28. This most useful metal is, by the 
wise Author of Nature, extensively diffused over the whole 
earth. It is found in combination with most earths and stones, 
and exists in vegetable and animal substances. Its ores are 
numerous, and exist in greater quantities than those of all other 

600. Metals of the third class but imperfectly understood. 

601. Review of the three classes of metals examined. Metals of the 
fourth class, how differing from the other classes ? 

602. Iron abundant in nature. Known to the ancients. Modern appli- 
cations of iron. 



ikon. 229 

metals, sometimes forming mountain masses. It appears to 
to have been known to the Hebrews, as early as the time of 
Moses; and other ancient nations were acquainted with its use. 
Its capabilities were, however very imperfectly known. The 
gradual application of it to the various objects of human inge- 
nuity and industry seems to mark the progress of the arts and 
sciences. The moderns only have applied it to the manufacture 
of printing presses, steam-engines, chain-bridges, watch springs, 
magnets, conductors of electricity, &c. &c. 

603. Properties. Iron is very infusible ; it has been melted 
at a heat of 158° of Wedgewood's pyrometer, which would be 
equivalent to 2200° F. It is an excellent conductor of caloric, 
and softens and dilates when heated. It is the only metal 
which takes fire by the collision of flint. It becomes heated by 
percussion. Sparks which appear when the smith draws from 
the forge a bar of iron at a white heat, are burning portions of 
the iron. Iron will burn in oxygen gas, with brilliant scin- 
tillations. There is no flame, because iron does not vaporize. 
It decomposes water, even at common temperatures. When 
iron filings are put into water, hydrogen gas is slowly evolved. 
Water in the state of steam, is rapidly decomposed by passing 
through iron filings in a heated gun-barrel, and for every grain 
in weight of the disengaged hydrogen, the iron gains 8 grains 
of oxygen, (see § 315.) 

604. Protoxide of Iron is the base of the native carbonate of 
iron, and the green vitriol of commerce. It was discovered by 
Gay Lussac, who, in heating the peroxide of iron with dry 
hydrogen gas, in a porcelain tube, found that water was formed, 
and the metal had lost a portion of oxygen. Its color is dark- 
blue, and when melted with vitreous substances, it gives them 
the same tint. It is less powerfully attracted by the magnet, 
than metallic iron. When exposed to the air, at common tem- 
peratures, it takes fire and burns vividly, absorbing oxygen, and 
becoming again the peroxide. 

When metallic iron is put into diluted sulphuric or muriatic acids, hydro- 
gen is evolved, and protoxide of iron formed. Its proportion of oxygen may 
be determined by collecting and measuring the gas which is evolved. Its 
salts, particularly when in solution, absorb oxygen with such rapidity that 
they are employed in eudiometry. 

605. Peroxide of Iron. In the composition of this oxide, we 
have one and a half equivalent of oxygen, with one of iron, (§ 

603. Effects of heat on iron. Combustion in oxygen. Decomposition of 
water by the action of iron. 

604. Protoxide of iron. Discovery. Properties. How may its propor- 
tion of oxygen be ascertained ? Affinity of its salts for oxygen. 

605. Peroxide of iron. 

20 



230 IRON. 

604,) a fact appearing at variance with the atomic theory, which 
does not admit of half an atom, and which gives 8 as the pro- 
portion by weight, in which oxygen unites with other bodies. 

606. We have formerly alluded to exceptions to this general law (§ 226.) 
According to the views there expressed, we may obviate the necessity of 
the fraction, by supposing a lower combining equivalent of oxygen, than has 
yet been admitted ; that is, calling the half equivalent, or 4, the atomic 
weight of oxygen ; this would give two equivalents of oxygen in the protox- 
ide, and three in the peroxide. This would not change the statement of 
relative proportions or chemical equivalents of any of the combinations of 
oxygen. But 8 seems, with very few exceptions to be the combining pro- 
portion of oxygen, and Chemists are not generally disposed to break up the 
arrangement now almost universally adopted, of considering the proportion 
of oxygen with hydrogen in water as its combining equivalent. 

The peroxide of iron, sometimes called red-oxide, exists in na- 
ture, and is known to mineralogists under the name of red- 
haematite. The brown- haematite is a hydrate of the peroxide of 
iron : ochres are mixtures of the hydrated red-oxide and clay. 

607. The peroxide may be made by dissolving iron in nitro-hydro-chloric 
acid, and precipitating by ammonia or other alkali, and then washing, dry- 
ing and calcining the precipitate at a low red-heat. When fused with vi- 
treous substances it imparts to them a red color. Its salts are mostly of 
the same hue. Iron rust is produced by the slow oxidation of the metal in 
the air, promoted by water, or the moisture of the atmosphere, and con- 
taining some carbonic acid. Black oxide of Iron. The black scales which 
appear after burning iron wire, or iron filings in oxygen gas, are a mixture 
of the blue and red oxides of iron, and in a variable proportion. Thus, on 
heating a bar of iron in the open air, the outer layer of the oxidated scales 
contains a greater proportion of the oxide than the inner ; this is because 
it was more exposed to the oxygen of the air. The native black oxide of 
iron is often found in crystals ; it constitutes the loadstone or magnetic iron. 

" On digesting this oxide in sulphuric acid, an olive colored solution is 
formed, containing two salts, sulphate of the peroxide and protoxide, which 
may be separated from each other by means of alcohol. These mixed salts, 
.give green precipitates with alkalies, and a very deep-blue ink with infusion 
of nut-galls. The black oxide of iron is the cause of the dull green color 
of bottle glass."— Turner. 

608. Chlorides of iron were formerly called dried muriates of iron. The 
proto-chloride is obtained by dissolving the metal in diluted muriatic acid, 
and thus obtaining proto-muriate of iron ; after evaporating the solution, the 
dried mass is heated to redness in a porcelain tube from which the air is 
excluded ; and in this state it is the proto-chloride of iron. 

The perchloride may be obtained by burning iron wire in chlorine gas. It 
is of a reddish color, and when dissolved in water, forms a red colored per- 
muriate or per-hydro-chlorate of iron. 

606. Remarks upon its half atom of oxygen. Synonymes. Hydrate of 
the peroxide of iron. Ochres. 

607. How may the peroxide of iron be formed ? Properties. Coloring 
property. Iron rust. Black oxide of iron, formed by the combustion of 
iron in oxygen or air. Native black oxide, or loadstone. Salts formed with 
this oxide and sulphuric acid. 

608. Synonymes of chlorides of iron. Proto-chloride. Per-chloride. Com- 
pounds of iron with bromine, iodine, and phosphorus. 



IRON. 231 

Iron unites with Bromine and Iodine forming a bromide, and iodide, and 
with phosphorus forming a phosphuret. The phosphate of iron (phosphoric 
acid with iron) is sometimes contained in the metal, and is injurious to it, 
by rendering it brittle at common temperatuies. 

609. Carburets of Iron. Iron combines with carbon in several 
proportions ; but the most important of these combinations are 
steel and plumbago. Steel is but the sub-carburet of iron and 
contains a lower proportion of carbon than any other compound. 
The proportion of carbon in steel is very small, not generally 
exceeding one pound, in one hundred and fifty. By fusion it 
forms cast-steel. The experiment has been tried of enclosing 
small diamonds in the cavities of soft iron, and igniting the 
mass ; the diamonds disappear, and the iron is converted into 
steel. This experiment shows, that the diamond and carbon 
are essentially the same substance ; and that it is the union 
of carbon with iron which forms steel. If a drop of any acid 
fall upon steel, the carbon is attracted by it, and a black 
spot appears. A drop of strong green tea will produce a black 
spot upon a steel knife. This is owing to the gallic acid con- 
tained in the tea. With pure iron acids do not produce the 
same effect. 

Plumbago or graphite was called black-lead from the common 
idea that its metallic appearance was owing to lead. The term 
is still used, though it is now known that plumbago contains no 
lead ; but consists of about 10 parts of iron, united with 90 of 
carbon. It is the percarburet of iron. It exists abundantly in 
nature, and may be formed by art, by exposing iron with char- 
coal to a violent and long continued heat. As plumbago is in- 
fusible in furnaces, it is used for crucibles. It is much used in 
the manufacture of pencils, and is employed in iron to protect 
it from rust. 

610. The proto-sulphuret of iron, or magnetic iron pyrites is of a brown 
color and metallic lustre. It may be obtained by fusing iron and sulphur 
together. It is much more fusible than pure metal ; hence if a bar of iron 
at a white heat, be rubbed with a lump of sulphur, the two substances com- 
bine, forming the proto-sulphuret, which melts and runs down in drops ( § 
480.) It is found in large quantities, in various parts of the United States. 
At Strafford, Vermont, there is an extensive manufactory of sulphate of iron, 
{green vitriol or copperas,) from a mine of the proto-sulphuret found in its 
vicinity. There is a similar mine on the east side of the Hilderberg moun- 
tain a few miles from Albany. 

The deuto-sulphuret, is the common iron-pyrites, which exists in great 
abundance in nature. It is of a yellow color, and often mistaken for gold. 

609. Iron with carbon. Steel. Iron changed to steel by heating with 
diamonds. Cause of the black spot produced by tea upon a steel knife. 
Plumbago. 

610. Proto-sulphuret of iron, &c. How obtained? Localities. Deuto- 
sulphuret. 



232 NICKEL. 

It cannot be artificially formed. When heated it loses one equivalent of 
sulphur, and is thus converted into the ^>ro/o-sulphuret. 

611. Though iron exists in almost every situation, pure 
native iron is seldom found. In meteoric stones magnetic iron is 
always found alloyed with nickel and cobalt, metals with which 
it is never associated in any iron ore found in the earth. This 
fact increases the interest that must be felt in these mysterious 
masses, which occasionally fall upon the earth. If, as some 
suppose, they be projected from distant volcanoes, why should 
they be unlike any other natural combinations which exist in 
mines or the bowels of the earth, as far as man has penetrated ] 
If they do not belong to the earth, from whence do they origi- 
nate 1 Some say from volcanoes in the moon, others that they 
are formed in the atmosphere, and others that they are little 
globules, which, like the earth, revolve around the sun, and fall 
through the atmosphere, because they come within the sphere 
of the earth's attraction. The iron found in these meteoric 
stones, is magnetic, as are also the cobalt and nickel combined 
with it. 

612. To obtain iron from its ores, for commerce, its oxides alone are re- 
duced. These are often combined with sulphur, arsenic, or some other 
substances which would render iron brittle. By roasting the ore, or sub- 
jecting it to a strong heat, these volatile su*bstances are expelled. It is then 
mixed with charcoal and lime at a high temperature. The charcoal absorbs 
the oxygen of the ore, and the lime acts as a flux by combining with silex, 
clay, and other impurities, and forms a fusible compound called slag. The 
melted metal, being heavier than the slag, sinks to the bottom of the fur- 
nace from whence it is drawn by means of a stop-cock. This is the cast- 
iron of commerce ; it contains some carbon and un-reduced ore. By a fur- 
ther process of heating, rolling and hammering it is softened, and converted 
into malleable or wrought iron. 

The Latin name of iron, ferrum, gives names to some of its compounds; 
as ferruginous earth, or earth which contains iron ; ferro-cyanic acid, com- 
posed of iron and cyanogen, &c. 

613. Nickel. — Equiv. 26. It is found in nature in the state of 
an oxide, and an arseniate ; but most abundantly, as a sulphu- 
ret united with arsenic, a small quantity of iron, copper, 
and cobalt. It is found in Chatham, Connecticut, associated 
with cobalt. It was proved to be a peculiar metal by Bergman, 
in 1775. Before that time, the ores containing it, had been sup- 
posed to be alloys of iron and copper. Hence its names kupfer 
nickel, copper nickel ; the term nickel being applied because it 

611. Pure native iron. Magnetic iron in meteoric stones. Opinions 
respecting the origin of these stones. 

612. Iron of commerce. How obtained? Cast and wrought iron. Latin 
name of iron and its compounds- 

613. Nickel, how found in nature ? When proved to be a peculiar 
metal ? Properties. Action with heat. Combination with oxygen. &c. 



zinc. 233 

looked like copper though it did not yield it. Like iron and 
cobalt, nickel is attracted by the magnet ; and may be rendered 
magnetic. It is difficult of fusion, though highly volatile. If 
heated to a red heat in contact with the air of oxygen, it be- 
comes an olive green oxide. 

It is supposed that nickel unites with oxygen in two definite proportions. 
It forms alloys with many of the metals. It has been remarked (§ 611) that 
meteoric stones contain nickel in combination with iron and cobalt. These 
metallic compounds are remarkable for bearing exposure to the weather 
without rusting. Large masses have lain in the open air, in Siberia, Pern, 
and Louisiana, apparently for ages, with very little appearance of rust. 

614. Zinc. — Equiv. 34. This metal, sometimes called spelter, 
is obtained either from calamine (native carbonate of zinc) or 
from zinc blende, the native sulphuret. As it is a volatile metal, 
it is always obtained by distillation. The zinc of commerce 
was formerly brought from China. It is now extensively 
manufactured in Europe. It is found in some parts of the 
United States, as in the Southampton, Mass. lead mines, with 
granite and gneiss j also in crystals in lime rock, near the 
Genesee river. It resembles lead but is of a lighter color. It 
melts at about 700°, and crystalizes when slowly cooled. When 
heated without being exposed to the air, it sublimes, without 
any change of properties. If heated in the air, it absorbs oxy- 
gen rapidly, exhibiting a beautiful flame of a brilliant greenish 
color, and the newly formed oxide flies upward, in the form of 
white flowers, formerly called flowers of zinc, or philosophical 
wool. When heated to a white heat, in a covered crucible 
placed in a furnace, on suddenly removing the cover, it bursts 
into flame and burns with a brilliant white light. The metal may 
be stirred with an iron rod to expose other portions of it to the 
air ; and then if held aloft, and poured slowly upon a brick or 
stone floor, it descends in a burning sheet, and is dashed about 
in a fiery spray. This metal is little affected by the air or 
moisture, and is therefore not liable to rust by exposure to them. 
On this account, it has been applied in the manufacture of 
kitchen utensils, and water pipes. But it is found to be attacked 
by fat substances, especially when aided by heat ; and also by 
the weakest acids ; its use is, therefore, become very limited, 
except in the laboratory. 

615. Sir H. Davy, on observing the peculiar property of zinc to resist 
corrosion, was led to make trial of it for the sheathing of vessels. Copper, 

614. From what mineral, and how is zinc obtained ? Zinc of commerce, 
where now manufactured ? Localities in the United States. Properties. 
Action of heat upon this metal. Why is zinc net liable to rust? What 
property of zinc prevents its extensive use for common purposes ? 

615. Effect of protecting the copper sheathing of ships from corrosion, by 
means of zinc. Objections to the use of zinc foi the sheathing of ships. 

20* 



234 zinc. 

which had hitherto been in use for that purpose, oxidizes so rapidly in water, 
as to become, in a short time, unfit for service. The copper was found to 
derive its oxygen from atmospheric air dissolved in water, while the oxide 
of copper thus formed, uniting with the muriatic acid of the sea water, 
produced a sub-muriate of the oxide of copper. If, by any means, the cop- 
per could be secured against oxidation, it would not form a salt with mu- 
riatic acid — and according to Davy's electro-chemical theory, it only com- 
bines with oxygen because, by contact with that body, it is rendered electro- 
positive. By rendering the copper negative, it would then be in the same 
electrical state as oxygen, and the two would have no tendency to combine. 
Davy accomplished his object of rendering copper permanently negative, by 
bringing in contact with it, zinc, which when the two metals were in this 
state of contact, was positive, and the copper, consequently, of the opposite, 
or negative electricity. Thus the oxidation of the copper sheathing, was 
found to be prevented by a small piece of zinc, no larger than the head of a 
nail, affixed to a sheet of 40 or 50 inches of copper. The copper was found, 
after many weeks of exposure to the action of sea-water, to be perfectly 
bright, whilst the zinc appeared to be slowly corroding. Triumphant as 
the success of this experiment at first appeared, it was found, on the appli- 
cation of it to practical purposes, to be attended with an unexpected embar- 
rassment, and that, unless a certain degree of corrosion took place on the 
copper bottom of the ship, its surface became foul from the adhesion of sea- 
weeds, and shell-fish. The salts of copper had in fact, served a useful pur- 
pose, in preventing these organic substances from fixing themselves in so 
poisonous a bed. Zinc plates have been substituted in the place of copper ; 
but they are found to be liable to an accumulation of organic substances. 
A merchant in New York, sheathed the bottom of a ship with zinc plates, 
fastened with zinc nails ; but she returned from her voyage so exceedingly 
foul, that he was obliged to remove the zinc, and substitute copper. Ma- 
rine vegetables and even large oysters were found adhering to the zinc. 
Thus, in the wise economy of the Almighty, that which cannot be decom- 
posed for the purpose of entering into new combinations, is used as a matrix 
to multiply and support organic existence. 

616. The protoxide of zinc is very rare in nature. It is ob- 
tained by the combustion of the metal in the open air. Thenard 
supposed that he obtained a deutoxide, and Berzelius describes 
a peroxide, but the former was admitted by its discoverer, to 
have had but an ephemeral existence, and the latter is consider- 
ed a form of the protoxide. 

Chloride of zinc, from its soft consistence, called butter of 
zinc, is formed by the combustion of zinc filings in chlorine gas. 
It is of an oily appearance, very volatile and deliquescent. Wa- 
ter changes it to the muriate of zinc. 

The natural sulphuret, called zinc blende, exists extensively 
in masses, and in crystals, which are sometimes semi-transpa- 
rent and afford beautiful gems. The white vitriol of commerce, 
is the sulphate of zinc. Its most important alloy is with copper, 
constituting brass; and in other proportions, pinch-beck, Dutch 
gold, &c. Its amalgam with mercury, is used for exciting 
electrical machines. 

61 6. Protoxide of zinc. Other supposed oxides. Chloride of zinc. Sul- 
phuret of zinc. White vitriol. Alloys of zinc. Amalgam. 



LEAD. 235 

617. Cadmium. — Equiv. 56. This was discovered by Stro- 
meyer, in 1818. During the reduction of zinc ore by charcoal, 
the cadmium, which is very volatile, flies off in vapor. Oxygen 
has no action upon it at the ordinary temperature, but when 
heated in the air, it burns with a yellow flame, forming an 
orange colored oxide. It is also oxidated by nitric acid, in 
which it is more easily dissolved than in any other acid. 

Oxide of cadmium, exists in nature, combined with carbonic acid and silica, 
in calamine, and other zinc ores. It may be obtained by heating the metal 
in contact with atmospheric air. Sulphuret of cadmium occurs native in 
some of the ores of zinc. M. Stromeyer obtained it by heating sulphur and 
cadmium. It was of a beautiful orange color, and on a careful evaporation, 
crystalized in transparent, gold colored laminae. It is thought by mineral- 
ogists that the Missouri lead mines may afford abundance of both zinc and 
cadmium. 

618. Cerium. — Equiv. 56. It is found in a rare Swedish 
mineral, called cerite. It has also been found with yttria in the 
yttro-cerite. Its qualities are little known. There are two ox- 
ides of cerium y the protoxide is a white powder. When heated 
in open vessels, it absorbs oxygen, and becomes the peroxide, 
which is of a fawn-red color. 



CHAPTER XXVI. 

METALS OF THE FOURTH CLASS CONTINUED. 

619. Lead. — Equiv. 104. This metal has been known from 
the earliest periods of history. It was called by the alchemists, 
Saturn; because, as this deity, (according to mythological 
fable,) devoured his children ; so lead, in the process of cupel- 
lation* absorbs, or devours most of the metals. The Latin 
name for lead is plumbum. 

Properties. Lead is of a bluish white color, and gives a dis- 
agreeable odor on rubbing j its specific gravity is 11.352. It is 

* The oxides of lead have the property of combining with most of the 
metals, except gold, silver, and platinum, and on this account are used for 
purifiers, by a process called cupellation, a term derived from cupel, the name 
of a peculiar kind of vessel used in the operation. In this process, the lead 
melts first, and carries with it, in fusion, all the baser metals. 

617. Discovery of cadmium. Oxide. Sulphuret. 

618. Cerium and its oxides. 

619. Alchemistical name of lead. Latin name. Properties. Action 
with heat, dry air and oxygen. Effect of moisture, combined with air or 
oxygen. Effects of fusing and heating in open vessels. Various uses. Ac- 
tion of acids upon lead. 



236 LEAD. 

soft and flexible, and has a strong metallic lustre, when recently 
cut ; but soon tarnishes, on exposure to the air. It is one of the 
most fusible of the metals ; melting much below red heat ; it 
crystalizes on cooling. Atmospheric air, and dry oxygen gas, 
have no action upon it ; but when moist, they soon cover it with 
a gray coat of the protoxide of lead. When fused in open ves- 
sels, a gray film is formed on its surface, which is a mixture of 
metallic lead and the protoxide ; and when strongly heated, it 
volatilizes in fumes of the yellow oxide of lead. 

On account of its abundance, and the facility with which it is 
wrought, lead is much employed in the arts. It is extensively 
used for aqueducts, reservoirs, chambers for the manufacture 
of sulphuric acid, printing types, and covering and sheathing 
gutters, and roofs of buildings. It is employed in medicine. 
Many of its compounds are poisonous to the human system. 

It has been asserted that leaden pipes for conducting water are unsafe, 
on account of the supposed danger of the water becoming impregnated with 
the metal and thus operating as a poison. Dr. Turner considers that the 
salts in spring-water, by gradually forming an insoluble film on the metallic 
surface of leaden pipes, effectually secure it against any change which 
would cause it to re-act upon the water. Lead is acted upon by acids, which 
promote its absorption of oxygen and carbonic acid from the atmosphere. 
Vinegar contains acetic acid ; and pickles should not, therefore, be kept in 
pots of earthen ware glazed with lead, as the acid corrodes the lead and 
forms poisonous salts. 

620. Protoxide of lead, exists in nature only in combination 
with acids forming salts. It is prepared in laboratories, by de- 
composing any salt of lead by potassa or soda. 

When first precipitated, it is white because it contains water or is hydra- 
ted, but when dried by heat and air it becomes yellow. This, in commerce, 
is called massicot. When the protoxide is partly fused in the air, it unites 
with about 4 per cent of carbon, and is called litharge ; The protoxide forms 
with acids all the salts of lead, most of which are white. It readily unites 
with earthy bodies when fused with them, forming the lead-glazing for pot- 
tery, Jlint-glass, and pastes for artificial gems. The protoxide of lead in- 
creases the refractive and dispersive power of glass more than any substance, 
so that the gems made with it resemble the diamond, but may easily be dis- 
tinguished by their inferior brilliancy and hardness. 

621.*Deutoxide of lead is formed by heating the protoxide 
in open vessels with free access of air. This is known in com- 
merce as minium or red lead. It is used in potteries for 
glazing, in the manufacture of flint glass, and as a paint for oil 
colors. It is also used for the coloring of red wafers which are 
consequently poisonous. Peroxide or tritoxide of lead is obtain- 

620. Protoxide of lead. Massicot. Litharge. Union of the protoxide 
with acids, and with earths. Use of the protoxide of lead in glass artificial 
gems. 

621. Deutoxide of lead. Red lead. Its uses. Peroxide of lead. Dry- 
ing oil. 



LEAD. 



237 



ed by digesting the deutoxide in nitric acid, which dissolves 
one part, leaving the other combined with a large portion of 
oxygen. This oxide is of a brown color, called puce or pea- 
colored. It is not used in the arts, or in medicine. 

Fixed vegetable oils, if heated with the oxides of lead, dissolve a portion 
of them, and are converted into what is called drying-oil. 

622. Chloride of Lead may be obtained by the action of chlo- 
rine gas on thin plates of lead. It is soluble in hot water, and 
is then considered a muriate of lead. A compound of the chlo- 
ride and protoxide of lead forms the paint called patent-yellow. 

The sulphuret of lead exists abundantly as a natural ore, called galena. 
This is the only ore which is wrought for the purpose of extracting lead. 
Galena is called potter's lead-ore, because it is used in pottery for glazing. 
This ore is abundant in the United States. The Missouri lead-mines are 
remarkable for their richness. There is a lead mine of considerable extent 
in Southampton, Mass. From specimens of galena found in that locality, 
we should infer that it might hereafter prove valuable, when improved pro- 
cesses for carrying on mining operations, and reducing metals, shall be bet- 
ter understood in this country.* 

The proportion of silver in lead ore is judged of by cupellation ; a small 
piece of metallic lead is heated under a muffle, upon a cup of ashes made 
by burning bones. The lead oxidizes, the oxide is absorbed by the ashes, 
and a button of silver remains. 

623. Lead forms vari- Fig. 101. 
ous alloys ; among the 

most important, is that - 

with antimony for printing 
types. With tin, lead 
forms alloys of different 
kinds, as pewter, in which 
tin constitutes more than 
half the compound, organ- 
pipes, tin foil, and nails 
used for some purposes 
in ship-building, because 
they do not rust in salt 
water. The solder of the 
tinner is composed of lead and tin. A compound of lead, tin and 
bismuth, melts below 212°, so that spoons made from it melt in 
boiling water. 

* In 1821, the author received from Charles Bates, Esq. some remarkably 
fine specimens of galena from the Southampton lead mine, and was inform- 
ed that the working of the mine had been attempted, but afterwards relin- 
quished on account of the difficulty and expense attending it. 




622. Chloride of lead. Muriate of lead. Patent yellow. Sulphuret of 
lead or galena. Lead mines of the United States. Silver obtained from 
lead ore by cupellation. 

623. Alloys of lead. Lead tree. How formed. Theory of the lead tree. 



238 copper. 

Lead is precipitated from its acid solutions both by iron and zinc. The 
had tree {or arbor saturni) * exhibits a beautiful arborescent crystalization of 
pure metallic lead, precipitated by means of zinc. A small lump of clean 
zinc (Fig. 101,) is suspended by a thread from the stopper of a transparent 
glass bottle, containing an ounce of the acetate of lead (sugar of lead,) dis- 
solved in a pint and a half of water. The lead is gradually precipitated upon 
the zinc, shooting forth into brilliant crystaline branches. The tree will 
continue to increase during several days, if the solution be suffered to stand 
undisturbed, and forms a beautiful and scientific ornament for a mantel 
piece. The precipitation of the lead, is at first, a chemical phenomenon. 
The zinc attracts the acetic acid from the solution of acetate of lead, and 
the lead is set free. The precipitation of the lead upon the zinc is supposed 
to be caused by galvanic influence. The two metals represent the two poles 
of the voltaic apparatus, and as the presence of diluted acid developes elec- 
trical agencies, a mutual attraction between the metals ensues. 

624. Copper. — Equiv. 64-. This is said to have been dis- 
covered in the isle of Cyprus and dedicated in heathen mytho- 
logy, to the worship of Venus; hence the alchemists termed 
this metal, Venus. The Latin name, copper or cuprum, is de- 
rived from Cyprus. The implements of war, and domestic 
utensils of the ancients were mostly made of bronze, or some 
other alloy of copper and tin. 

Copper is found pure in native masses and crystals, it is the 
only metal, except titanium, which is of a red color; it is very 
malleable, ductile, and elastic, and is the most sonorous of the 
metals. When rubbed, it emits a peculiar, nauseous odor. The 
pure metal and its compounds are all poisonous. It fuses at a 
white heat, and if the heat is urged further, it volatilizes in visi- 
ble fumes. On cooling slowly, it crystalizes in quadrangular 
pyramids. Copper filings thrown into a strong fire, burn with 
a green flame. It does not strike fire with flints, and is there- 
fore used for the nails, hammers and other implements used in 
the manufacture of gunpowder. But when exposed to the com- 
pound blow-pipe it burns with a green flame, and light too in- 
tense for the eye. On account of the color of its flame the 
salts of copper are sometimes used in artificial fire-works. 

Copper is little changed by a dry atmosphere ; but when exposed to air 
and moisture, it becomes thinly coated with a green sub-carbonate. As this 
metal is poisonous, culinary vessels of copper should never be used except 
when perfectly clean, or well tinned. When heated to redness, copper 
oxidizes, and becomes covered with brown scales. 

625. The red protoxide of copper may be obtained by igniting 

* Tree of Saturn. 

624. Origin of the name copper. This metal known to the ancients. 
How found in nature ? Color and other properties of copper. Action with 
heat. Why copper nails and hammers used in operations connected with 
the manufacture of gun powder. Combustion of copper. Color of the 
flame. Formation of sub-carbonate of copper. Copper vessels for culinary- 
purposes. Oxidation of copper. 

625. Protoxide of copper. How obtained ? 



COPPER. 



239 



in a close vessels 64 parts metallic copper with 80 parts of the 
peroxide, the metal takes from the peroxide 1 portion of oxygen, 
and the latter is thus reduced to the protoxide, of which, as 64? 
added to 80=144, there are 144 parts. 

626. The protoxide of copper is dissolved by some of the acids, as also 
by ammonia ; in solution with the latter it is colorless : but, on exposure 
to the air, it becomes blue, owing to the formation of the peroxide. The 
salts of the protoxide rapidly absorbs oxygen from the air, and become per- 
salts; that is, the base of the salt changes from the protoxide to the perox- 
ide, and the salt is, in consequence, changed from a protosalt to aper-salt. 
The protoxide exists in nature ; beautiful crystals of it are found in the 
mines of Cornwall, and in Connecticut and New Jersey. 

627. Peroxide, or black oxide of copper, is formed by expos- 
ing the metal, for some time, to red heat, in the open air. The 
peroxide of copper is insoluble in water: it does not give the 
alkaline test with blue vegetable color, but unites acids to form 
salts ; these salts are either green or blue. With ammonia, it 
forms a deep blue solution, a property which is peculiar to the 
peroxide of copper, and which affords a valuable test. It is pre- 
cipitated of a yellowish white color, by albumen, so that the 
white of eggs, and other substances containing albumen, are an 
antidote to the poison of this salt of copper. 

628. The proto-chloride of copper may be prepared by heating copper 
filings with twice their weight of per-chloride of mercury, (corrosive subli- 
mate.) The perchloride may be obtained by digesting the proto-chloride in 
muriatic acid, and exposing the permuriate of copper, which is thus formed 
to a temperature of about 400° F. It. is deliquescent in the open air, and 
becomes again the permuriate, by absorbing moisture, thus changing from 
white to green. 

Sulphuret of copper is a constituent of variegated copper ore. It may be 
prepared by fusing copper and sulphur together. 

Bi-sulphuret is of a yellow color, and more common as a native produc- 
tion, than the sulphuret. It exists in copper pyrites combined with proto- 
sulphuret of iron. 

The alloys of copper are numerous j that with zinc, forming 
brass* is perhaps the most important. With tin, copper forms 
bronze, cannon-metal, bell-metal, and coating for the interior of 
copper vessels, and metallic mirrors. With gold or silver, it 

* The manufacture of brass has been practised from remote ages. The 
ancients confounded copper, brass, and bronze. Brass was, in their view, 
only a more valuable kind of copper, and they often used the word ces, to 
denote either. 

626. Action of the acids and ammonia on the protoxide of copper. Salts. 
Existence in nature. 

627. Peroxide of copper. Properties. Action with ammonia. With 
potassa and albumen. 

628. Chlorides of copper. Proto-chloride. Per-chloride. Sulphuret. Bi- 
sulphuret. Alloys. Metals which precipitate copper from its solutions 
Verditer, &c. Native copper. Copper of commerce. 



240 MERCURY. 

forms coin, and gold and silver ornaments. Zinc, tin, and es- 
pecially iron, precipitate copper from its solutions. 

Exp. Immerse the blade of a knife in a solution of copper, and it will be 
instantly covered with the metal. The blue paint, verditer, is the hydrate of 
copper with a little lime. Native copper exists in various parts of the Uni- 
ted States. According to Silliman, it has been found near New Haven, 
Connecticut, and near lake Superior, and other localities in that region. 
The copper of commerce is usually obtained from the sulphurets. 

629. Bismuth. — Equiv. 72. The name is supposed to be a 
corruption of the German weissmuth, or white mother of silver. 
It was formerly called glazed tin. It is brilliant, of a yellowish- 
white color, and very brittle. It is very fusible. At a hi^n 
heat, and in close vessels, it may be completely volatilized. 
When melted in the air, its surface becomes covered with a 
greenish brown oxide. 

Oxide of bismuth may be obtained by burning bismuth in the 
open air, and collecting the fumes. The yellow oxide which is 
thus obtained, was formerly called flowers of bismuth. 

When the nitrate of bismuth is mixed with water, a precipitate is formed 
of the sub-nitrate, known as the pearl white, (or blanc defard,) of perfumers ; 
from its pearly whiteness it is used as a cosmetic. It is injurious to the 
skin, and is also liable to assume a tawny hue, in contact with sulphuretted 
or phosphuretted hydrogen ; thus, the effluvia from boiled eggs, and some 
mineral springs, and even sitting before a fire of mineral coal, may change 
a brilliant artificial white complexion, into a mulatto color. When the pow- 
der of bismuth is heated with chlorine gas, a pale blue light appears, and a 
white chloride of bismuth is formed, which from its oily appearance, was 
formerly called butter of bismuth. 

Bismuth is found in the earth in the form of pure ore, of an oxide, a sul- 
phuret, and an arseniate. The only known American locality of native bis- 
muth, is at Munroe, Connecticut. 

630. Mercury. — Equiv. 200. The common name is quick- 
silver. The alchemists named it from the planet mercury. 
They imagined that by solidifying, it would form silver. The 
Latin name, hydrargyrum, (from the Greek udor, water, and 
argenon, silver,) denotes that it was supposed to be liquid silver. 
Boerhaave is said to have held it in digestion twelve years, in 
order to obtain a solid precipitate of silver. The alchemists, 
however, in their vain attempts to change mercury into silver, 
made many important preparations, which are of great use in 
medicine, and in the arts. 

Properties. Mercury is the only metal that is fluid at the 
common temperature of our climate. At 40° below zero, F., a 
cold which sometimes prevails in the polar regions, mercury 
becomes solid, and forms octahedral crystals. It can also be 

629. Origin of the name bismuth. Properties. Oxide of bismuth. Pearl- 
white, &c. Localities. 

630. Origin of the name mercury. Opinion of the Alchemists, &c. Pro 
perties. Effect of temperature, &c. From what obtained, &c. 



MERCURY. 241 

congealed by artificial means. In a solid state, it is malleable, 
and may be cut with a knife ; applied to the skin, it produces a 
sensation no less painful than that of red hot iron. If a small quan- 
tity of solidified mercury be thrown into a glass of water, it melts, 
while the water is frozen by the loss of its latent heat, and 
the glass is shivered to pieces. Mercury is white and brilliant, 
like polished silver. The clean surface of a vessel of mercury, 
is a most perfect and splendid mirror. Its principal ore is the 
sulphuret or cinnabar from which it is separated by the action 
of heat upon quick-lirne and iron filings. The presence of mer- 
cury in ores, may be easily ascertained, as it volatilizes before 
the blow-pipe. 

631. On account of the great weight of this metal, it affords 
the most perfect means of demonstrating the statistical and 
moving force of fluids and caloric, is essential in the construction 
of the barometer, and forms the most useful thermometer. The 
mercurial cistern for collecting gases, is necessary in many 
chemical experiments. 

The specific gravity of mercury at 47° F., is 13. 568. It contracts in 
congealing, so that its specific gravity is increased to 15.612; thus, frozen 
mercury sinks in the fluid metal. The boiling point of mercury seems to 
be about 650°, or a little more than three times the heat of boiling water. 
Its vapor condenses on cool surfaces, in minute metallic globules. The 
usual method of purifying mercury, is by distillation. Its vapor is very ex- 
pansive, having a specific gravity of 6 97, air being considered as unity, or 
1. If mercury be heated in strong iron vessels, closely covered, the force 
of its expansion will burst the vessels. Mr. Faraday proved that mercury 
volatilizes slightly, without the application of heat. By exposing gold leaf 
for some time over a vessel of mercury, he found the gold leaf whitened. 

632. Mercury, at the common temperature, is not tarnished 
by atmospheric air or oxygen gas ; but at a boiling heat, it grad- 
ually becomes a red oxide. Sulphuric and nitrous acids, act 
upon mercury. The former has no action upon it in the cold ; 
but on the application of heat, the mercury absorbs a portion of 
oxygen from the acid, sulphurous acid is disengaged, and a sul- 
phate of mercury formed. Nitric acid, without the aid of heat, 
oxidizes and dissolves mercury, with a disengagement of the 
deutoxide of nitrogen. 

Oxides of mercury were formerly called mercurial calcs* 
Protoxide, or black oxide of mercury, is formed when mercury 

* Metallic calcs, (from calx,) were metals which had undergone the pro- 
cess of calcination or combustion, or some equivalent operation. 

631. Uses of mercury. Specific gravity. Boiling point. Vapor of mer- 
cury. Volatilization of mercury without heat. 

632. Oxidation of mercury. Oxides of mercury. Protoxide. Peroxide. 
Exp. Thenard's theory of this process. Decomposition of the peroxide by 
heat. 

21 



242 MERCT7RY. 

is violently agitated, for a long time, in contact with the atmos- 
phere. 

Peroxide, or red oxide may be obtained by exposing the metal 
to heat in the open air. 

Exp. The peroxide of mercury may also be obtained by the following pro- 
cess. Mercury is dissolved in nitric acid, and the nitrate so formed is 
exposed to heat, red fumes are given off, and the peroxide of a beautiful red 
color appears. The theory of this change, is thus explained by Thenard.* 
The nitrate of mercury used in this process, is a mixture of the nitrates of 
protoxide and deutoxide, (peroxide,) of mercury ; when exposed to nearly 
red heat, the nitric acid changes to oxygen, and nitrous acid gas ; the 
latter, not being retained by the oxide of mercury, is disengaged in the 
form of red fumes ; the oxide, now changed by another proportion of oxy- 
gen to the deutoxide (or peroxide,) of mercury, remains in the form of deep 
red scales, called red precipitate. When heat will disengage no more ni- 
trous acid, (which acid is easily known by its color and peculiar odor,) the 
operation is completed, and the peroxide is to be preserved in closely stop- 
ped bottles. When heated to redness, it is converted into metallic mercury 
and oxygen, in the proportion of 16 parts of the latter, to 200 of the former. 
The peroxide is much employed in medicine. 

633. Proto-chloride of mercury, calomel, was formerly, called 
white precipitate of mercury. It may be formed by bringing mer- 
cury in contact with chlorine gas, at common temperatures; al- 
so by adding a solution of common salt to a solution of mer- 
cury in nitric acid. A white heavy powder is precipitated, which 
is tasteless, and insoluble in water, and sublimes by heat, with- 
out decomposing. 

Bichloride or perchloride or corrosive sublimate may be obtain- 
ed by heating mercury in chlorine gas, during which process 
the metal burns with a pale red flame. In constitution, it differs 
from calomel only, in 1 additional equivalent of oxygen ; but its 
properties are widely different. Its taste is highly acrid and 
burning ; it is corrosive to animal substances, and a strong poison. 
The best antidote is albumen. 

Exp. Place a drop of the suspected liquid on polished gold, and touch the 
moistened surface with a piece of iron wire or the point of a pen-knife, the 
part touched will instantly become white, owing to the formation of an 
amalgam of gold. 

* Traite. de chimie, Tome II. p. 392. Most elementary writers on Chem- 
istry, state the process for obtaining the peroxide of mercury from the ni- 
trate, without attempting any theoretical explanation. Silliman, (Elements 
Vol. II. p. 314 and 315.) considers "the nitrate as a compound of peroxide 
and per-nitrate." This he says is decomposed by heat, till all the fumes 
cease, and then (page 307) " the oxide will become of a beautiful red color." 
He does not state the nature of the decomposition which takes place ; nor 
how, by means of it, the whole remaining mass is brought to the state of a 
peroxide. 

633. Protochloride. Perchloride. How obtained. Difference in the 
constitution of corrosive sublimate and calomel. Properties of corrosive 
sublimate. Exp. 



MERCURY. 243 

Some animal and vegetable solutions convert the bichloride into the pro- 
tochloride (that is change the corrosive sublimate to calomel) as the albumen 
of eggs with water. " The caustic nature of corrosive sublimate seems ow- 
ing to its action on animal muscles and membranes." — Turner. Nitrate of 
silver produces with it a white precipitate, chloride of silver and alkalies a 
yellow precipitate, and hydrochloric acid a black sulphuret of mercury. 

634. Bicyanuret sometimes called the cyanide, cyanuret, or prnssiate of 
mercury is obtained by boiling red oxide of mercury, with twice its weight 
of prussian blue in solution, until the blue color of the latter disappears. 
The colorless solution of the bi-cyanuret of mercury which is formed, crys- 
talizes in four sided prisms, when carefully evaporated. Theory. Prussian 
blue is the hydro-ferro-cyanate of iron. The oxygen of the oxide of mercury 
unites with the iron and hydrogen of the ferro cyanic acid ; while the me- 
tallic mercury, and cyanogen, being both disengaged, enter into combina- 
tion. The peroxide of iron remains in the form of a brown, insoluble mass. 
It has a disagreeable, metallic taste, and is very poisonous. When heated 
with sulphur, 1 part of the cyanogen is disengaged, and sulpho-cyanuret of 
mercury formed. 

635. Theproto-sulphurets of mercury, formerly called Ethiop's 
mineral, may be prepared by adding to melted sulphur, its own 
weight of mercury. The bi-sulphuret, is the cinnabar, or ver- 
milion of commerce. 

It is very valuable in the arts as a paint. It is found in nature, and by 
its decomposition, affords most of the mercury of commerce. By mixing 
with iron tilings, and heating the mixture, the sulphur passes to the iron, 
and the mercury is obtained by sublimation. Native cinnabar is usually 
found in secondary geological formations. 

636^\dtloys of mercury with other metals, are called amalgams. The af- 
finities of metals for mercury differ. Some, as gold, silver, and tin, form 
amalgams with mercury, by mere contact; but in most cases, the fusion of 
the metal is necessary. Heat decomposes amalgams by volatilizing the mer- 
cury. The amalgam of tin and mercury, is fluid at a low heat, which facili- 
tates its use as a coating for glass, to form mirrors. This process is called 
silvering. 

Exp. Pour mercury upon a sheet of tin-foil, press it with a weight for a 
few hours, and the amalgam will be found adhering to the glass from the 
force of attraction. Articles of gold and silver, when exposed to mercury, 
lose their peculiar lustre and become tarnished.* 

* Some years since the author was invited by Prof. Silliman, to visit the 
extensive laboratory of Yale College. Being then unacquainted with the 
amalgamating nature of mercury, and encouraged by the Professor's exam- 
ple, she was about to thrust her hand into the metallic liquid of the large 
mercurial cistern, when he exclaimed, " take care of your rings," and thus 
saved her from the chagrin of seeing her gold rings turned to a pewter-color. 

634. Bicyanuret of mercury. Synonymes. How obtained? Theory of 
the process. 

635. Sulphurets of mercury. 

636. Alloys of mercury. Amalgams. Silvering. Exp. 



244 SILVER. 

CHAPTER XXVII. 

FOURTH CLASS OF METALS CONTINUED. 

637. Silver, — Equiv. 110. The alchemists called this metal 
Diana or Luna, (the moon,) on account of its white lustre. 
Thus, the nitrate of silver is called lunar caustic. From the 
Latin name argentum, the term argentine is often applied to 
compounds of silver. Silver is of a brilliant white color, more 
malleable and ductile than any metal except gold. It may be 
extended into leaves less than 1 ^ 00 of an inch in thickness, 
and drawn into wire finer than a human hair. Its specific 
gravity is 10.39. It may be volatilized by a very strong heat 
continued for some time. Neither air nor moisture oxidize 
silver ; when exposed to the action of voltaic currents, it burns 
with a beautiful light-green flame, and combining with oxygen, 
forms the oxide of silver. The silver of commerce always con- 
tains a small alloy of copper, in which state it is wrought by the 
silversmith. Silver is used as one of the precious metals, and 
for various useful and ornamental purposes. 

638. Though silver is not easily affected by oxygen, it tarnishes in con- 
tact with sulphur and sulphurous compounds. Hence the dark color im- 
parted to silver spoons by boiled eggs, the whites of which contau^some 
sulphur. Nitric and sulphuric acids, oxidate this metal, forming with it 
lunar caustic, nitrate of silver, and sulphate of silver. 

639. Silver is often found pure, in a native state, frequently 
sulphuretted, often alloyed with other metals, such as gold, an- 
timony, and sometimes blended with sulphuret of lead, and cop- 
per pyrites. In Mexico and some other countries, it only needs 
melting to obtain it pure. Silver is extracted from lead ores by 
cupellation, and from ores where lead is not present, by amalga- 
mation. There is some silver in the lead ores found in various 
parts of the United States; but no silver mines have yet been 
discovered. The Andes of South America, and the Cordilleras 
of Mexico are very rich in native metallic silver. 

640. Oxide of Silver may be obtained by precipitating a so- 
lution of the nitrate of silver by potassa or soda. It is of an 
olive green color, and insoluble in water. When heated to 
redness, the oxygen is exploded, and the metal revived. There 

637. Names of silver and its combinations. Precious metals. Proper- 
ties of silver. Combustion of silver by means of galvanism. Silver of com- 
merce. Uses. 

638. Action of sulphur upon silver. Action of nitric and sulphuric acids. 

639. Silver as existing in nature, and native combinations. Extraction 
of silver from ores. Localities of metallic silver. 

640. Oxide of silver. Exp. 1. Exp. 2d. 



SILVER. 245 

is but one oxide of silver composed of one equivalent of silver 
and one of oxygen, and therefore considered the protoxide of 
silver. Silver, when in solution with nitric, or sulphuric acid, 
is precipitated in the metallic state by copper and mercury ; it 
then assumes an arborescent appearance, called the silver tree 
or arbor Dianas. 

Exp. 1. Put a globule of silver into a white glass vessel with a dilute 
solution of lunar caustic, (nitrate of silver) ; let it stand undisturbed a few 
days, and a beautiful silver tree will appear. 

Exp. 2d. Immerse a bright copper cent or wire in a solution of the 
nitrate of silver, it will be covered with white crystals. 

641. Fulminating Silver, or ammoniuret of Silver, is a very dangerous 
preparation, exploding by blood heat, or by the slighest touch. It is 
formed by adding strong liquid ammonia to oxide of silver. The phenome- 
non of detonation, is ascribed to the action of the oxygen upon the hydro- 
gen of the ammonia, forming steam, which is suddenly exploded, along with 
the nitrogen and metallic silver. 

The detonating silver first prepared by M. Descotils is made by dissolving 
silver in a small quantity of nitric acid, and heating the solution with an 
equal bulk of alcohol ; on coolin?, a crystalline powder falls, which must be 
washed, and dried on blotting paper. M. Liebig and Gay Lussac consider 
the fulminating and detonating compounds, to be composed of the oxides of 
the metals and a peculiar acid, which they call fulminic acid, and that they 
are therefore salts. "The great explosive powers of these compounds/' 
says Silliman, u probably depend upon the mutual re-action of the elements 
producing aeriform bodies, which are suddenly evolved, and their evolution 
is not probably connected with electrical agency."* 

642. Chloride of Silver is produced when silver is heated in chlorine gas, 
and may also be prepared by mixing hydrochloric acid with a solution of 
nitrate of silver. It is at first white, but becomes black when exposed to 
the sun's rays, disengaging hydrochloric acid and forming oxide of silver. 
The chloride of silver when found native is called horn silver. A mixture 
of this chloride with chalk and pearlash is employed for silvering brass; 
such as thermometer scales, clock dials, &c. 

643. Silver forms alloys with all the metals except nickel. 
Silver coin is composed of about -^ part of copper. Silver 
vessels and ornaments are fashioned by hammering, as silver 
does not cast well. Silver plate has a large alloy of copper. 

* Silliman's Ele. Vol. II. p. 339. Professor Silliman, who was seriously 
injured in making one of these preparations, suggests that great caution 
should be used with respect to them ; and remarks that " the little fire 
crackers or torpedoes are very improperly made subjects of amusement 
among boys. A twisted paper contains the fulminating silver mixed with 
sand to produce attrition, and to disguise the powder, and a lead shot to 
give it momentum, when it is thrown ; still, to a person unacquainted with 
the subject, the paper presents nothing to the eye but a shot and some sand, 
with some minute white fiocculi, which might well escape the eye of a com- 
mon observer." 

641. Fulminating silver. Detonating silver of Descotils. Opinions of 
Liebig and Gay Lussac and Prof. Silliman. 

642. Chloride of silver. 

643. Alloys of silver. Silver coin, vessels, <fcc. Silver plating. 

21* 



246 GOLD. 

644. Gold. — Equiv. 200. Latin, Aurum ; French, or; cal- 
led by the alchemists so/, the sun, or king of metals. It has 
been known from the most remote periods. The Peruvians and 
Mexicans, when first visited by the Spaniards, were acquainted 
with gold and silver, though ignorant of iron and its uses. Its 
physical properties had been long known, before its chemical 
relations were thought of; the latter were developed in some 
degree, by the labors of the alchemists. Gold is distinguished 
from all the other metals by its yellow color. It exceeds them 
all, in ductility and malleability. 

It has been computed that 14,000,000 films of gold, like the coating of 
fine gold wire, would not exceed one inch in thickness, while the same 
number of sheets of common fine writing paper would form a thickness, 
of about | of a mile. The specific gravity of gold is a little over 19. It 
is the heaviest of the metals except platinum. It is more fusible than 
silver, being fused by the common blowpipe, when it is of a dark «reen 
color. It may be volatilized by the heat of a current of oxygen gas, direct- 
ed upon burning charcoal; if a plate of silver be held over the vapor, it 
will become gilded. 

645. The only solvents of gold are aqua regia, nitrohydro- 
chloric acid, and liquid chlorine. According to Sir H. Davy, 
hydrogen of the hydrochloric acid leaves the chlorine and 
forms water with a portion of the oxygen of the nitric acid, re- 
ducing it to nitrous acid. The liberated chlorine, then acts 
upon, and dissolves the gold, forming with it a chloride of gold. 

646. The peroxide of gold unites more readily with alkalies 
than with acids : and is, therefore, by some considered an acid, 
called auric acid, and its salts, aurates. 

In this case, gold should be transferred to our 1st class of metals, or those 
which form acids with oxygen. But most chemists consider this compound 
as a tritoxide, consisting of three atoms of oxygen, 24, to one of gold, 200, 
making its equivalent 224. It is obtained by boiling a solution of the chlo- 
ride of gold with magnesia ; the oxide remains in the state of a yellow hy- 
drate. It is rendered anhydrous by boiling, and then assumes the charac- 
teristic brown color of the peroxide. It is insoluble in water, combines 
readily with alkalies, but unites sparingly with acids. A powerful electric 
discharge through sold leaf or wire laid between papers, gives rise to a pur 
pie substance which has been called the purple oxide of gold. This purple 
oxide is considered by some a deutoxide, and by others to be merely gold in 
a state of minute sub-division. 

647. Chlorides of Gold. Gold leaf introduced into chlorine 
gas, takes fire and burns ; and if it be suspended in water into 
which the gas is passed, it is dissolved, and the solution may 
be concentrated by evaporation. This is probably the perchlo- 
ride. By exposure to a moderate heat, it parts with two thirds 

644. Synonymes of gold. This metal early known. Properties. 

645. Solvents of gold. Theory. 

646. Oxides of gold. 

647. Chlorides of gold. 



GOLD. 247 

of its chlorine, and is converted into a yellow insoluble proto- 
chloride. 

648. The perchloride was formerly called muriate of gold. The saturated 
solution of gold in nitro-hydrochloric acid yields crystals of a deep orange 
color which rapidly attract moisture from the air. Heat expels the chlorine, 
and the gold remains as a spongy mass. The action of solar light is suffi- 
cient to reduce this chloride, and the glass which contains it, when it is thus 
exposed, will become lined with a brilliant coat of the revived gold. The 
solution of perchloride of gold is often used in the arts, for gilding by the 
agency of substances which, having a strong attraction for oxygen absorb 
it from the water of the solution, leaving the hydrogen to form hydro-chlo- 
ric acid with the chlorine, and thus precipitating the gold. Mrs. Fulharae 
gilded ribbons by moistening them with a solution of muriate of gold by 
means of a camels hair pencil, and holding them over hydrogen gas as it 
was evolved. 

649. The protochloride of tin, precipitates the perchloride of gold a beauti- 
ful, purple color forming what was formerly called precipitate of cassius, and 
stamiate of gold. It is this compound which gives to glass and porcelain a 
rich pink-color: When potassa is added to the solution of perchloride of 
gold, part of the gold, uniting with the oxygen of the potash, is precipitated 
in the state of an oxide, while the remaining portion of the gold and the 
whole of the chlorine combining with potassium, form a double chloride of 
gold and potassium. 

Liquid ammonia forms, with the solution of gold, a brownish precipitate 
called fulminating gold. 

Exp. If ether be poured into a solution of perchloride of gold, it unites 
with the metal, and an etherial solution of gold floats on the surface of the 
hydro-chloric acid. This was anciently called auriferous ether. It is some- 
times used for gilding delicate steel instruments. 

650. Gold may be combined with iodine, bromine, sulphur and phospho- 
rus. Sulphur does not act on gold as readily as upon silver ; the sulphuret 
of gold is formed by passing a current of sulphuretted hydrogen through a 
solution of chloride or muriate of gold. 

651. Gold forms alloys with many of the metals. Antimony 
and zinc destroy its ductility. Bismuth produces with it a 
brittle, pale, yellowish green alloy. Tin, or bismuth render it 
spongy, and diminish its specific gravity. The fumes of lead 
give to gold externally a pale yellow, and internally a brown color, 
and render it very brittle. When united with iron, gold be- 
comes magnetic, and harder than steel. Copper is united to 
gold in coin, usually in the proportion of -&. Nickel in a certain 
proportion, forms with gold an alloy resembling brass. Mercury 
readily unites with gold. A gold ring becomes white by mere 
contact with mercury. This amalgam may be destroyed by ex- 
posing it to heat ; the mercury volatilizes, and the gold remains 
unchanged. Silver gives to gold a paler color ; and, in a cer- 

648. Perchloride of gold. 

649. Precipitate of perchloride of gold with the protochloride of tin. Pre- 
cipitate with potassa, &c. Precipitate with liquid ammonia. Exp. 

650. Combination of gold with iodine, bromine, &c. Sulphuret of gold. 

651. Alloys of gold. Carats of gold. 



248 PLATINUM. 

tain proportion, produces with it the green alloy of the gold 
smith. 

The fineness of gold is expressed by the number of parts of gold which it 
contains. It is supposed to consist of 24 parts called carats. Thus 24 
carats fine, is pure, unalloyed gold. If it has 8 parts of alloy, it is said to 
be 16 carats fine. The native gold of North Carolina is 23 carats fine. 

652. Gold is never found in combinations with earthy and 
siliceous minerals j but exists either in a pure metallic state, or 
alloyed with other metals. It is sometimes found crystalized 
in cubes or octahedrals united in little groups, but more com- 
monly in thin scales, spangles or dust. It is found in primitive 
mountains, and in the sand in the beds of rivers, of alluvial for- 
mations, having been washed down from the mountainous re- 
gions. It occurs in veins of lead, and silver, and with iron 
pyrites. The most extensive gold mines, are those of Mexico, 
Peru, Transylvania, and Hungary. Gold is found .in the sands 
of Brazil, mingled with platinum and diamond. A rich and ex- 
tensive region of gold exists in the United States ; it was dis- 
covered in North Carolina, but it has been traced north to Vir- 
ginia, and south to Alabama and Georgia. 

653. Gold may be purified from mixture with the baser metals, by melt- 
ing it with nitre, and by cupellation with lead ; also by dissolving in nitro- 
hydrochloric acid, filtering the solution, and adding proto-sulphate of iron, 
which precipitates all the gold in the metallic state, leaving the other metals 
in solution. Gold is separated from silver with greater difficulty than from 
any other metal ; but when an alloy of gold and silver is dissolved in nitro- 
hydrochloric acid, the silver is found in the form of a white, insoluble chlo- 
ride, and the gold in solution. 

654. Platinum. — Equiv. 96. Was first discovered by the 
Spaniards, near the river La Plata* in South America. It 
was first carried to Europe in 1741, by Mr. Wood, an assay- 
master at Jamaica, though it had been previously described by 
Don Ulloa, who accompanied some French academicians to Peru 
in 1735. 

Properties. Platinum is the heaviest of all known substances. 
Its specific gravity is somewhat over 20. It has a silvery 
whiteness, is very ductile and malleable, and so soft that it may 
be cut with scissors, or scratched with the nails. It is infusi- 
ble by ordinary means, and does not oxidize with the most 
intense heat of the furnace. 

Thus crucibles which are to be exposed to intense heat are made of pla- 
tinum. It is also a less perfect conductor of caloric than most of the me- 
tals, and on this account, and its infusibility, is used for spoons and tongs 

* The word plata signifies silver. 

652. Gold, as found in nature. Geological localities of gold. Geogra- 
phical localities. Gold mines in the United States. 

653. Modes of purifying gold. 

654. Discovery of platinum. Origin of the name. Properties. Uses. 



PLATINUM. 249 

for holding substances exposed to the action of the blow-pipe. Thin leaves 
of platinum, are used for wrapping substances that are to be exposed to 
great heat. The scarcity of this metal, which renders it nearly as expen- 
sive as gold, prevents its being generally used, except for a few chemical, 
and scientific purposes. 

655. Like iron, platinum admits of being welded at a high 
temperature ; at a white heat, an imperfect fusion takes place, 
which covers its surface with a kind of varnish, so that when 
different pieces are brought together in this state, they may be 
forged with a hammer, and thus be made to combine perma- 
nently. A piece of platinum-wire melts when exposed in the fo- 
cus of the compound blow-pipe like wax in a common lamp j it 
scintillates, drops in melted globules, and a portion rises in 
vapor. It is fused by powerful lenses, and by concave mirrors. 
It fuses also with fluxes, as borax, and glass, and if kept com- 
pletely enveloped in charcoal, it may be melted in that sub- 
stance. Its only solvents are chlorine, and nitro hydrochloric 
acid. 

656. The protoxide of platinum is prepared by digesting protochloride of 
platinum, in a solution of pure potassa. The precipitate is found to consist 
of 96, or one equivalent of metal, and 8, or one equivalent of oxygen. The 
equivalent, therefore, of the protoxide of platinum, is 96 Pla. added to 8 ox. 
= 104. This result is obtained by expelling the oxygen with heat, collect- 
ing and weighing it, and then weighing the pure metal which remains. 
This proves also that 96 is the combining equivalent of platinum. 

The peroxide is found on decomposition, to yield 16 parts, or 2 equivalents 
of oxygen, to 96 parts, or one equivalent of metal. The protoxide is black, 
the peroxide is of a brownish yellow color, when in the state of a hydrate ; 
but on becoming anhydrous by drying it is black. The peroxide is obtained 
with difficulty ; for on attempting to precipitate it from the muriate by 
means of an alkali, it either falls as a sub-salt, or is held together in solution. 
Like peroxide of gold, it is a very feeble base, and is much disposed to unite 
with alkalies. — Turner. 

657. Chloride of Platinum. Platinum does not take fire when 
introduced in thin leaves into chlorine gas, but a slow combus- 
tion of the two substances takes place, forming a chloride. 
When platinum dissolves in nitrohydrochloric acid, a chloride 
is formed. This is the perchloride ; it is soluble in water, and 
decomposes with light. When heated, it gives up a portion of 
chloride, and becomes the protochloride. 

When a solution of hydrochlorate of ammonia is added to the 
perchloride of platinum, a light yellow precipitate is formed, 

655. Welding of this metal. Fusion of platinum by the compound blow- 
pipe, &c. 

656. Protoxide. Peroxide. 

657. Modes in which the chloride of platinum may be formed. Per-chlo- 
ride. Protochloride. Double hydrochlorate of platinum and ammonia. 
Spongy platinum. Prof. Dobereiner's invention. Theories to account fi>» 
the action of hydrogen on platinum sponge. Fulminating platinum. Com- 
binations of platinum with phosphorus, &c. 




250 PLATINUM. 

commonly a double hydrochlorate of platinum and ammonia. 
When heating this to redness chlorine and hydrochlorate of 
ammonia are evolved, and pure metallic platinum remains in 
a spongy mass, called spongy platinum, remarkable for its power 
of igniting a mixture of oxygen and hydrogen gases, and also 
the vapor of ether and alcohol. 

Fig. 102. This peculiar property of platinum 

sponge was discovered in 1824, by 
Prof. Dobereiner, of Jena, and by 
him applied to the construction of 
lamps, for the production of instan- 
taneous light, by means of a simple 
and ornamental apparatus. It is com- 
posed of two glass vessels (Fig. 102) 
a and b. The vessel a, is encompass- 
ed by a coil of zinc in the tubular 
extremity which extends nearly to 
the bottom of the lower vessel, b. 
Sulphuric acid being poured into the 
lower part of the apparatus, the 
smaller vessel is then inserted, its 
tube being so fitted to the neck of the 
other vessel, by grinding, as to be air 
tight. Hydrogen gas is now evolved by the action of the zinc upon the 
water of the sulphuric acid, and by its pressure, forces part of the liquid into 
the upper vessel through its tube. On opening the stop-cock, c, the gas 
issues forth in a jet, which inflames the spongy platinum contained in a 
brass cup at p ; the platinum ignites the stream of hydrogen, and the latter 
lights the taper which is situated between p and c, or in the current of burn- 
ing hydrogen. A candle or taper applied to the jet, may be lighted at any 
moment, by turning the stop-cock to allow the hydrogen gas to escape. 

It has been suggested that the minutely divided spongy platinum, by ab- 
sorbing a large portion of hydrogen in its pores, generates heat, which the 
oxygen of the air kindles into flame. Another theory supposes that the 
sudden ignition of the hydrogen, arises from a galvanic action taking place 
between that and the platinum ; the hydrogen acting the part of the zinc 
plate. 

Fulminating platinum is formed by decomposing sulphate of platinum by 
excess of ammonia. One grain heated to 400° Fahrenheit, explodes with a 
flash, and a report louder than that of a pistol. 

Platinum unites with phosphorus and mlphur in two proportions; and is 
capable of combining with most of the metals. 

658. The ore of platinum is found in nature, combined with 
four recently discovered minerals, viz : iridium, rhodium, palla- 
dium., and osmium, and also iron and chromium. It is usually 
seen in flat grains, seldom in pieces so large as an ounce weight. 
It has been found most abundantly in South America and in Si- 
beria, where it exists in auriferous (or gold bearing) sands, near 
the Uralian mountains. The four recently discovered metals found 
in connection with platinum, are yet little known ; and have been 

658. Ore of platinum, with what metals combined, &c. 



IRIDIUM. 251 

procured, but in small quantities. When platinum ore is digest- 
ed in nitro-hydrochloric acid, the platinum, together with the 
palladium, rhodium, iron, copper, and lead, is dissolved ; while 
a black powder, consisting of osmium, and iridium, remains. 
These various metals are separated and purified by very difficult 
and complicated processes. 

659. Palladium, is of a silver color. Vauquelin observed that 
under the gas blow-pipe it burnt with an appearance of brilliant 
coronas, or aigrettes of flame. When a jet of hydrogen is passed 
upon spongy palladium, the metal reddens, and water is formed, 
by the combination of the hydrogen with the oxygen of the air. 
Palladium is acted upon by several of the acids, but most power- 
fully by the nitro-hydrochloric. 

The oxide of palladium forms with potassa beautiful red salts. 
Berzelius discovered two chlorides of palladium. This metal 
also has been combined with sulphur, and several other metals. 
Palladium was first introduced into England by Dr. Wollaston, 
in 1S03 ; and named after the planet Pallas, then recently dis- 
covered. 

660. Rhodium. Dr. Wollaston obtained this metal from pla- 
tinum ore, during the period in which he was making observa- 
tions upon palladium. Vauquelin and Berzelius have since ex- 
amined it. It is named from the Greek rodon, a rose, on account 
of the rose color of its chloride. 

6G1. Thomson states that there are two oxides of rhodium; the black 
protoxide, and the yellow peroxide. According to Berzelius, there are two 
chlorides, the one yellow, and the other red ; they are formed by passing 
chlorine gas over the metal. 

662. Iridium. The name of this metal, is from iris, the rain- 
bow so called on account of the changeable hue of its salts. It 
was discovered by M. Descotils, in 1803. On digesting plati- 
num ore with nitro-hydrochloric acid, a portion, in the form of 
a black powder, remains undissolved j this consists of a mixture 
of iridium, and another metal, called osmium. Iridium is very 
infusible. It was melted by Mr. Children's powerful galvanic 
battery, and appeared as a brilliant, porous, metallic mass, whose 
specific gravity was 18.06. It is remarkable for its hardness, 
and for its power of resisting the action of acids ; on account 
of which properties, it is used for the points of metallic pens, as 
other metals soon become corroded by the gallic acid contained 

659. Properties of palladium. Spongy palladium. Oxide. Chlorides, &c. 
Introduction into England. Name. 

660. Rhodium. 

66 1 . Oxides of Rhodium. 

662. Derivation of the name iridium. Discovery. Found in platinum 
ore. How fused ? Properties, &c. 



252 CLASSIFICATION OF METALS. 

in ink, and the pens are thus rendered unfit for use. The pecu- 
liar hardness of platinum is supposed to be caused by the pre- 
sence of iridium. According to Berzelius, solutions of iridium 
may, without the aid of any foreign substance^ be obtained of all 
the hues of the rainbow. 

663. Osmium. The name from the Greek os?ne, odor, was 
given on account of the strong odor of one of its oxides, resem- 
bling that of chlorine. Berzelius, by passing the oxide of os- 
mium, mixed with hydrogen gas, through a heated glass tube, 
obtained a compact precipitate of osmium, having a metallic 
lustre. When heated in the open air, it oxidizes, and dissipates 
in vapor. Berzelius states that there are at least, three oxides 
of osmium, containing 1, 2, and 4 equivalents of oxygen. He 
considers the oxide which emits the strong odor, as the deu- 
toxide. 

Osmium heated with chlorine, forms a chloride, of a beautiful blue color; 
if heated with an excess of chlorine, a red perchloride sublimes. It unites 
with sulphur, and forms ductile alloys with gold and silver. This metal in 
solution, when tested with nut-galls, becomes first purple, and then blue ; 
with ammonia, it changes to a yellow color. 

664. Latanium, is a newly discovered metal prepared by Mozandes, froca 
the nitrate of latanium. 



665. CLASSIFICATION OF METALS. 

CLASS I. CLASS II. 

Metals which form acids with oxygen. Metals whose oxides *ve fixed alkalies, or oJ- 

■Equiv. kaline earths. 

Arsenic. 38 order i. Metals whose oxides are fixed alka- 



lies. 



Antimony. 44 

Columbian,. 144 Potassium. ^76 

Sodium. 24 



Titanium. 



S7"!\ iuin ' 32 Lithium . 10 

Molybdenum. 48 

Tellurium. 32 

Tunaalpn Oft order ii. Metals whose oxides are alkaline 

lun^sien. yo earths. 

Vanadium. Equir. 

Uranium. 208 Barium. 70 

Manganese. 28 Strontium. 44 

Cobalt. 26 Calcium. 20 

Tin. 58 Magnesium. 12 

663. Origin of the name osmium. Osmium obtained in a metallic state. 
Its oxidation. Oxides of osmium. Chlorides, and other compounds of os- 
mium. Tests of osmium. 

664. Latanium. 

665. What metals of the 1st class ? 2d Class, 1st Oraer. 2d Class, 2d 
Order. 3d Class. 4th Class. 



REMARKS. 


CLASS III. 


Cadmium. 


Metals whose oxides are earths. 


Cerium. 


Equiv. 


Lead. 


Aluminum. 10 


Copper. 


Zirconium. 


Bismuth. 


Glucinum. 


Mercury. 


Yttrium. 


Silver. 


Thorium. 


Gold. 


CLASS IV. 


Platinum. 


Metals whose oxides are neither acids, alka- 
lies, nor earths. 


Palladium. 


Equiv. 


Rhodium. 


Iron. 28 


Iridium. 


Nickel. 26 


Osmium. 


Zink. 36 


Latanium. 



253 

56 
50 

304 

64 

72 

200 

110 

200 

96 

56 

44 



666. We have now completed a brief examination of the me- 
tals. In an elementary course little more can be expected, than 
that the pupil will gain a knowledge of general principles, and 
become familiar with a sufficient number of applications to illus- 
trate these, and impress them upon his memory. But such 
knowledge is of inestimable value. It furnishes the master-key 
which will enable him, hereafter, to enter into nature's labora- 
tory and examine for himself the wonderful operations which 
are there going on. He has learned to avail himself of the aids 
which the labors of others afford him ; and may consider him- 
self as standing at that point where the greatest chemists, who 
have preceded him, once stood. There was a time when they, 
too, were beginning to learn; when observation of the power of 
chemistry to effect the most simple change in the elements 
around them caused their bosoms to dilate with emotions of de- 
light ; and the thought to spring up in their minds, " If science 
can do this, what can it not perform 1" A glorious future of 
discovery and invention dawned upon their fancy, and they fol- 
lowed with untiring steps through labors and difficulties, until 
success and honor crowned their efforts. Let not the American 
student fold his arms beneath the mantle of indolence, imagining 
that Lavoisier and Davy, Vauquelin and Berzelius have discov- 
ered all that is to be learned in this department of human know- 
ledge. He should rather consider, that their discoveries and in- 
ventions have put into his hands important instruments, for the 
development of new facts, and the discovery of new principles. 

The God of Nature, who has placed no limits to man's desire 
of knowledge, renders also, the field of inquiry equally illimita- 
ble. One newly discovered region in science opens a pathway 
to many others, and thus there is, and ever must be, an infinite 
progression in knowledge, suited to the capacities of the im- 
mortal mind, and corresponding with the character and dignity 
of an infinite Creator. 

666. Remarks. 22 



254 CRYSTALIZATION. 

SALTS. 
CHAPTER XXVIII. 

CRYSTALIZATION. CLASSIFICATION OF SALTS. SALTS OF THE 
OXACIDS. 

CRYSTALIZATION. 

667. Having now examined the elementary substances with 
their union with each other, called binary compounds, we shall 
proceed to describe the secondary compounds formed by the 
union of three or more simple bodies. ^ These compounds are called 
salts. As salts under certain circumstances assume crystaline 
forms, the subject of crystalization may properly precede the 
description of them. 

Crystals are formed of similar particles of matter, which, ac- 
cording to some wonderful and unknown law of nature, arrange 
themselves into regular, geometrical forms. There is nothing 
in organic nature more admirable than that process of inorganic 
matter in which each particle takes its proper place, in order to 
form, by aggregation, that kind of figure which is peculiar to its 
own species of matter. The law of molecular attraction may 
account for the aggregation of particles, but it does not explain 
why, under certain circumstances they always arrange them- 
selves in perfect symmetry j nor can any satisfactory reason be 
given for this phenomenon. 

668. Solid bodies appear under a variety of forms. In the 
vegetable and animal kingdoms, figure is the result of organiza- 
tion. The plant bursting from the seed, puts forth roots, stem, 
leaves, and flowers ; and the animal, exhibits its head, limbs, 
and peculiar features. In both, organic laws prevail, and a liv- 
ing principle converts inorganic matter into nourishment, as- 
similating it to the substance with which it incorporates. In 
the mineral kingdom, solids are either irregular, amorphous* 
masses, in which the particles cohere without regular order, or 
exhibit a crystaline structure. 

669. Exp. 1st. Dissolve crystals of alum, (a double salt of alumine and 

* From the Greek a, destitute of and morphe, regular shape. 

667. Substances which have been examined, compounds to be described, 
&c. Formation of crystals. 

668. Forms of organic bodies. Forms of minerals. 

669. Effects of slow and sudden evaporation. Exp. 1st. Exp. 2d, and Exp, 
3d. Crystals with truncated angles and edges. 



CRYSTALIZATION. 



255 



potash) and suffer the solution to evaporate slowly, you will have the same 
octahedral (eight sided) crystals as those dissolved. But if the liquid be 
expelled by a sudden and strong heat, you will find the salt in a shapeless 
mass, or in confused and irregular crystals. 

Exp. 2d. Plunge a lump of alum into a tumbler of cold water, let it re- 
main undisturbed a few days and you will find the surface of the salt eaten, 
and carved out into a variety of regular forms. (See fig. 103.) 

Exp. 3d. Let a few drops of a solution of alum, be put upon a glass 
plate ; in a few days, the particles of alum when examined with a microscope, 
will be found to have arranged themselves in small octahedra (eight sided 
figures,) (see fig. 104.) Crystals are liable to certain modifications ; thus 
in octahedral figures we may find some whose angles are truncated, or ap 
pear as if they were cut off or replaced by secondary surfaces ; sometimes 
the edges are also similarly modified ; at A, (fig. 105,) angles only of the oc- 
tahedron are truncated, at B, the edges . only, at C, both the angles and 
edges. 

670. As the soluble salts when thus evaporated, usually assume distinct 
figures, crystalization gives to the chemist and mineralogist a valuable me- 
thod of determining the composition and nature of different bodies. The 
smallest crystals obtained from a drop of solution, are equally perfect in 
figure as the largest ones, formed in greater quantities of the fluid; and, 
when viewed through a microscope, furnish evidence, equally satisfactory, 
of the nature, of the crystalized salt. 

Fig. 103. Fig. 104. 




671. Different salts may be thus conveniently evaporated in separate 
small glasses, and their different crystals compared. 

Exp. Take common salt, (chloride of sodium,) Glauber's salt, (sulphate of 
soda,) Epsom salts, (sulphate of magnesia,) and nitre, (nitrate of potash,) of 
each a teaspoonful, and put them into separate wine glasses with water ; 



670. Advantages afforded by crystalization to the chemist and mineralo- 
gist. Small crystals equally perfect in form as larger ones. Comparison of 
the crystals of different salts. 



256 



CRYSTALIZATION. 



occasionally stir the mixture, to facilitate their solution, and when the salts 
are entirely dissolved, put a drop of each solution upon a clean watch glass 
placed in the sun. As the liquid evaporates, crystals peculiar to each kind 
of salt, may be seen with a microscope ; common salt will appear in cubes ; 
Glauber's salt in irregular six sided prisms ; Epsom salts in four sided prisms ; 
nitre in six sided prisms ; (see fig. 106.) Glauber's salt and nitre, though 
resembling each other in the form of their crystals, exhibit a marked differ- 
ence when exposed to the air ; crystals of the former effloresce, that is they 
lose their transparency, and crumble to powder, while those of the latter are 
not changed by the atmosphere. Nitre is anhydrous salt, that is, it contains 
no water of crystalization. 

Fig. 106, 




?2° D 









* * « 



Crystals of Epsom salts. 



Crystals of common salt 





Crystals of Glauber's Salt. 



Crystals of Nitre. 



672. Crystals, in respect to forms, are divided into primitive 
ox fundamental and secondary or derived forms. It is found that 
though the same substance, may assume different crystaline 
forms, these are, in general, allied to each other. 

Fig. 107. 673. The most, common primitive 

forms are the four sided prism, cube, 
rhomboid, tetrahedron, octahedron, rhom- 
boidal dodecahedron, dodecahedron with 
triangular /aces, and the triangular 
prism. 

The four sided prism, (Fig. 107,) has 
its sides composed of four equal oblong 
parrallelograms, and its ends of two 
square parallelograms ; it is sometimes 
called a square prism. The cube has 
six square equal sides. 




671. Crystals of various salts. 

672. Division of crystals in respect to forms. 

673. Most common primitive forms. Four sided prism. 



Cube. Rhom- 



CEYSTALIZATION. 



257 




Rhomboid. 
The octahedron, i 



Tetrahedron. 



The rhomboid (Fig 108,) has 
its opposite sides equal and par- 
allel, but none of these are 
square, each having two acute 
and two obtuse angles, while 
each side of the cube has four 
right angles. 

The tetrahedron (Fig. 108,) is 
included within four, equilateral 
triangular planes. 



ight sided figure has all its planes equal, and similai 
triangles. It may be considered a compound of the tetrahedron. The cut 
(Fisr. 109,) represents a crystal of this form shaded, and the same in outline. 

The hexangular, or six sided prism ; in this, the six sides are similar par 
allelograms, not square, but oblong ; it has six edges and six angles ; that 
is, it is hexahedral and hexagonal. 

The rhombic dodecahedron : has twelve sides ; each plane being a rhomboid 
having two acute, and two obtuse angles. 

The dodecahedron with triangular faces has twelve, equal, triangular sides, 

b Fig. 109. 





fd 



Hexangular Prisms. 




Rhombic dodecahedron. Dodecahedron with triangular faces. 

nrimnnk. The primitive forms of crystals might be 

considered under the three general classes ; 
the triangular or most simple prism, the 
tetrahedron or most simple solid, and the 
parallelopiped. (Fig. 110.) 

674-. To some one of these varie- 
ties of forms, all crystals, by me- 
chanical division may be reduced. 
Triangular Prism. Parallelopiped. Discoveries in crystalography, as 

boid. Tetrahedron. Octahedron. Hexangular prism. Rhombic dodeca- 
hedron. Dodecahedron with trangular faces. Triangular prism. Tetrahe- 
dron. Parallelopiped. 

674. Circumstances which have led to discoveries in crystalography. 
The Abbe Hauy led to examine the structure of crystals. Planes, edges 
and angles. 22* 





258 



CRYSTALIZATION. 



in other departments of science, have been, in part, the result of 
accident. Gahu, a Swedish professor of mineralogy accident- 
ally broke a piece of dog-tooth-spar,* and found it was an ag- 
gregate of rhomboidal crystals. The Abbe Hauy, a celebrated 
French philosopher, when examining an expensive collection of 
minerals, let fall a beautiful crystal, which separated into many 
pieces ; struck with the smooth and brilliant surfaces of these 
fragments, the Abbe was led to an examination of the structure 
of crystals. He found that all crystals are easily divided in 
certain directions, leaving smooth and regular surfaces ; that 
the smaller crystals thus obtained, may again be divided inio 
other minute crystals ; but the same form is observed in all. 
Thus calcareous-spar, crystalizes in rhomboids, fluor-spar, in 
cubes, and quartz in six-sided pyramids. 

The surface of a crystal is called its pi ane or face. The lines 
made by the meeting ot two planes are called edges ; the meet- 
ing of three planes forms what is called a solid angle. 

Fig. 111. Fig. Ill; shows a cube in which a, a, a. are planes, b. 6, 

are edges and c c, solid angles. Thus the cube has six 
planes or faces, twelve edges, and eight solid angles. 

675. The primary cubic form may be modified by va- 
rious circumstances. The three primary forms (see § 
673,) were by Hauy considered as belonging to the inte- 
grant molecules of all crystahne bodies. " But it is not 
difficult, as Dr. Wollaston suggests, to conceive that 
these primitive forms may, themselves, be procured by 
c b c certain arrangements of spherical particles. 

Thus, four balls arranged as at c, (Fig. 112,) give the element of the te- 
trahedron. 

Six balls, arranged as at b f that of the octahedron, &c. 
Fig. 113, represents a number of spherical particles aggregated to form 
the tetrahedron and triangular prism. 

Fig. 114, represents the rhomboid and cube. 

Fig. 115, the octahedron and four sided prism formed in a similar manner. 
Instead, therefore, of assuming several distinct geometrical solids as primi- 
tive forms, some philosophers refer to the sphere, or spheroid, as the source 
of all, and assume it as the figure of the ultimate, mechanical particles of 
matter." 

Fig. 112. Fig. 113. 



a 
i 


a 

\ 


N - 





Crystaline carbonate of lime. 



675. Modifications of the primary form. Hauy's opinion respecting the 
primary forms. Dr. Wollaston's suggestion. Opinion of some with respect 
to the figure of ultimate atoms. 



CRYSTALS. 



259 



Fig. 114. 



676. The secondary forms of crys- 
tals are supposed to grow out of 
the integrant molecules and primi- 
tive forms, as follows. The mole- 
cules first unite, to produce the 
primitive form, and from this pro- 
ceeds the secondary form by the 
application of successive layers of 
the integrant molecules, parallel 
to its planes and faces. (Fig. 116.) If a cube be increased by layers of 
particles applied to all its sides, the edges of the layers being parallel to 
those of the cube and each layer being made less than that immediately 
preceeding it, by one row of particles on each of its edges, a dodecahedron, 
or twelve sided solid, with rhombic faces will be produced, (Fig. 116.) 

Fig. 116. 





Fig. 115 




Rhombic Dodecahedron. 

677. Crystals not only differ one from another, in form, but those of 
similar form differ in the angles made by the inclination of the faces. Thus in 
the rhomboid, which is characterized by having one of its adjacent angles 
smaller than a right angle and the other larger, it is evident that the one 
angle may consist of almost any number of degrees less than 90, and the 
other of any number below 180, though this must be the amount of the two 
angles taken collectively ; because the four angles of the crystal, must, 
together, be equal to four right angles, thus 90x4—360, which is the num- 
ber of degrees of a circle, by which angles are measured. Thus the primi- 
tive form of calcareous spar is a rhomboid whose faces are inclined at an- 
gles of 105° 5', which is more than a right angle, and 74° 5', which is less 
than a right angle, these numbers added together make 180°, which is the 
sum of two right angles. The primitive form of the mineral called tourma- 
line, is an obtuse rhomboid, the largest angle of which is 113° 10'. 

678. An instrument (Fig. 117,) called a goniometer* has been invented 
for measuring the angles of crystals. Its operation is founded upon the 
mathematical proposition! that " the opposite angles made by any two lines 

* From the Greek gon an angle, and metron measure, 
f Euclid, B. I. prop. 15. 

676. Manner in which the secondary forms proceed from the primary. 

677. Crystals of similar form may differ in the size of their angles. 

678. Goniometer. Reflective goniometer. 



260 



CRYSTALS. 




Fig. 117. j n crossing each other are 

equal." Thus the angle made 
by the arms B B, B C B, of 
this instrument, above and be- 
low the pivot on which they re- 
volve, are equal to each other. 
Therefore if the angle of a 
crystal be placed at C, and 
the arms of the goniometer 
made to close upon its planes, 
a similar angle will be made by 
the arms on the opposite side, 
and this angle may be known 
by examining the semicircle, 
A A, which is graduated into 
180°. An instrument called 
Goniometer, or instrument for measuring the angles t he reflective S^eter has 
of crystals. been invented by Dr. YYollas- 

ton, which measures with great accuracy the angles of the most minute 
crystals; here instead of the crystal itself being employed as a radius, rays 
of light reflected from the brilliant angles are made subservient to this 
purpose. 

679. In order to obtain large and well formed crystals, three things are 
necessary, time, space and repose. 

**§• H°' 680. We have considered the subject 

"^^^^^ffllMMflMFOfilfflllTllTi^^^ °* cr y stanzat ' on chiefly in respect to 
vM ff/lJffiffflnn'f'f'l'' l 'f UiUjilitl/m '////////////i^^F^ salts ' but metals often assuiJQ e very 
H|^^^^^^^^^y|l((||||[|p/ beautiful, and regular crystaline forms. 

This may take place either by liquefy- 
ing them by fusion, or by converting 
them into vapor ; and as the liquid be- 
comes solid by cooling, or the vapor by 
condensing, the particles arrange them- 
selves in crystals of greater or less re- 
gularity. Tin, lead, antimony, and bis- 
muth, all afford crystals. For this pur- 
pose they may be melted in a crucible ; 
when the surface cools it should be 
== pierced, and the liquid metal within 
poured out ; when the hollow mass has 
become quite hard, it may be broken and the interior of the cavity will be 
found lined with crystals. Fig. 118, represents the crystalization of bismuth 
effected in this manner. 

681. Crystals are to the mineralogist, what flowers are to the 
botanist. He reads the chemical constitution of minerals in the 
mechanical figure which they present, as the botanist decides 
by the organs of the plant, the class or group to which it be- 
longs. But as various accidental circumstances, to which 
flowers are not exposed, affect the forms of crystals, it is often 




679. To obtain perfect crystals. 

680. Crystalization of metals. 

681. Value of crystals to the mineralogist. 



SALTS. 261 

necessary that the inquirer should examine the constituent parts ; 
and this can only be done by the aid of chemical analysis. 

Classification of Salts. 

682. To facilitate the study of the salts, they hare, very pro- 
perly, been arranged in groups, or genera. As every acid, with 
few exceptions, unites with every alkaline base, the different 
kinds of salts thus formed are very numerous, amounting to 
more than 2.000, though not more than thirty were known a 
hundred years ago. The names given to the salts were, often, 
merely arbitrary ; but in the present nomenclature, the name of 
a salt expresses its composition, and the knowledge of its composi- 
tion recals its name. The name of the genus is derived from the 
acid, that of the species, from the base ; thus sulphate is a 
generic term, including various species, as sulphate of soda, 
sulphate of lime, &c. « 

683. The acids are divided into two classes ; 1st Oxacids, 
or those acids in which oxygen is united to a combustible body ; 
2nd Hydracids, or acids composed of hydrogen and some other 
substance. Until the great revolution in chemical science, 
which took place about the year 1775, it was supposed that oxy- 
gen was the only acidifying principle. Bertholiet was the first 
to suggest doubts on this subject, by affirming that sulphuretted 
hydrogen ought to be regarded as an acid, though composed of 
hydrogen and sulphur. The discovery of iodine and chlorine, 
furnished new and convincing proofs that the acidifying pro- 
perty is not confined to oxygen, but exists in other bodies. 
The number of the binary oxacids amounts to more than twenty, 
while that of the hydracids is much less. 

684-. There are four orders of salts viz : — 

Order I, Salts of the oxacids. 
Order II, Salts of the hydracids. 
Order III, Haloid Salts. 
Order IV, Sulpho Salts. 

Every acid is capable of forming a salt with a base ; and such salt may 
be considered as a distinct genus ; but as one element often forms with 
oxygen several acids, which though they possess individuality, are very 
similar, we shall consider the various salts formed by such acids as con- 

682. Importance of some mode of classifying salts. Difference between 
the old names of the salts and those which are founded on the chemical 
nomenclature. 

683. Two classes of acids. 

684. Orders of salts. What constitutes a general character in respect 
to salts ? Subgenera of salts. 



262 SULPHATES. 

etituting divisions of a genus ; thus the nitrites and hyponilrites will be 
classed as subgenera, of the genus nitrate. 

ORDER I. SALTS OF THE OXACIDS. 

GENUS I. SULPHATES. 

85. Of all the acids, none has a more decided tendency to 
combine with salifiable bases, than the sulphuric. The number 
of sulphates is of course very great. 

Properties. They have mostly a brittle taste ; and are decomposed by 
baryta, which has a stronger affinity for sulphuric acid, than any other 
base. All the sulphates may be decomposed by carbon, at a high tempera- 
ture. The acid and oxide are both decomposed, the oxygen forming with 
the carbon, carbonic acid, and the sulphur forming with the metal, a sul- 
phuret. At common temperatures, the sulphates neither effervesce with 
acids nor give off vapors ; but the sulphuric acid, by a high heat, may be 
displaced by boracic, phosphoric, and arsenic acids. Those which contain 
no water of crystalizalion, as the sulphate of iron, when exposed to great 
heal, yield a portion of anhydrous, sulphuric acid. Six of the sulphates are 
insoluble in water, viz : the sulphates of baryta, tin, antimony, bismuth, lead, 
and mercury ; the sulphates of lime, strontia, silver, and a few others are 
sparingly soluble; all the others are soluble in water. The soluble sul- 
phates form with hydrochlorate of baryta, a dense white precipitate, which 
is the sulphate of barytas, and is insoluble. 

Among native sulphates, those of lime and baryta are most 
abundant. Those which are employed in the arts, are usually 
extracted from native minerals. Some are prepared directly by 
art, and many by double decomposition. 

686. Sulphate ofpotassa, is a white salt, of an acrid and bitter 
taste; it was formerly much valued in medicine and is known 
in commerce, as vitriolated tartar. It is of use in the manufac- 
ture of alum, glass, and salt petre. It is not found native among 
mineral substances, but exists in the ashes of tobacco and some 
other vegetables. The bi-sulphate contains twice as much acid 
as the sulphate. 

687. Sulphate of soda was discovered by Glauber, a German 
chemist in the process for obtaining muriatic acid, by decompo- 
sing common salt with sulphuric acid. A precipitate of soda 
was obtained which has been named Glauber's salt in honor of 
its discoverer. It is contained in the waters of some mineral 

685. Why is the number of sulphates great ? General properties of this ge- 
nus of salts. Decomposition, &c. Insoluble sulphates. Soluble sulphates 
with muriate of baryta. Native sulphates, ifec. 

686. Properties of sulphate of potassa. Uses. Where found. 

687. Discovery of sulphate of soda. Common name. Where it exists in 
nature. Properties. Crystals. Degree of temperature at which water 
most readily dissolves it. Effect of the effervescence of this salt. Uses. 
Bisulphate of soda. 



STJLPHATE OF LIME. 263 

springs, in sea water, in the ashes of sea weed, and sometimes 
effloresces at the surface of the earth, and upon the walls of cel- 
lars, and other excavations. It exists in a mineral found in 
Spain, called Glauberite. 

It is a colorless, and very bitter salt, capable of forming very large crys- 
tals, and containing 58-100th of the water of crystalization. According to 
Berzelius, the crystals are composed of 72 parts, or one equivalent of sul- 
phate of soda, and 90 parts, or ten equivalents of water. They undergo the 
watery fusion on exposure to heat. This salt readily effloresces in the air. 
It is one of the essential medicines of the family dispensatory. It is used 
in the arts for the preparation of carbonate of soda, and manufacture of 
glass. BisuJphate of soda is formed by adding sulphuric acid to a solution 
of sulphate of soda. 

688. Sulphate of ammonia exists in small quantities in nature ; 
in the neighborhood of volcanoes, and in the waters of the 
Tuscan lakes. It is usually prepared by the direct combination 
of ammonia with sulphuric acid. 

689. Sulphate of Baryta, called heavy spar is an abundant pro- 
duct of nature usually found in veins, with metals, sometimes 
in fibrous masses. It is wholly insoluble in water, and bears 
the most intense heat without fusion, or decomposition. 

The affinity of pure baryta for sulphuric acid, is so great, that when they 
are brought in contact, ignition is produced. This affinity enables baryta 
to separate sulphuric acid from all its combinations, giving a white precipi- 
tate, in a solution containing no more than one millionth part of baryta. 
All the salts of baryta, except the sulphate, are poisonous; and this excep- 
tion is owing to the perfect insolubility of the salt, in the juices of the sto- 
mach. If, therefore, any of the poisonous salts of baryta be swallowed, 
diluted sulphuric acid, a solution of sulphate of soda, or any other alkaline 
sulphate, would be the proper antidote. The sulphuric acid would unite 
with the baryta of the poisonous salt, and form the harmless sulphate of 
baryta. 

690. Sulphate of Lime is abundant, existing in the form of 
gypsum, (plaster of Paris,) alabaster, and silky crystals, called 
selenite. It is found in the ashes of plants, and the water of 
springs, causing what is called the hardness of the latter. 

Hard water, or that which contains salts, and consequently acids in solu- 
tion, decomposes soap, while the oil combining with the earthy base of the 
salt, floats on the surface of the water ; thus it is impossible to form, what 
the laundress calls suds, with hard water. Add soap to a solution of sul- 
phate of lime, and the soap will immediately be decomposed. Sulphate of 
lime may be formed by adding sulphuric acid to any carbonate of lime, or 
lime water. When pure it is perfectly white, as in alabaster. Exposed to 
intense heat, it loses its water of crystalization, and fuses into a white 
powder ; in this state it forms plaster of Paris. 

688. Sulphate of ammonia. 

689. Sulphate of baryta. Why not poisonous. 

690. Existence of sulphate of lime in nature. Hardness of water. Pre- 
paration of sulphate of lime. Plaster of Paris. Composition of anhydrous 
sulphate of lime. Of the crystalized sulphate, Anhydrite. Uses of sul- 
phate of lime. Plaster casts. 



264 SULPHATE OF ALUMINA. 

Anhydrous sulphate of lime consists of one proportion of aeid=40, one 
proportion of lime=28. The compound equiv. is, therefore=68. The crys- 
talized sulphate contains, in addition, two proportions of water, -=18, ma 
king its equivalent 68 added to 18=86. 

The uses of sulphate of lime are various. It is employed as a manure for 
soils ; and with lime plaster to give it a greater durability, firmness, and 
smoothness; this composition for walls and ceilings is called hard finish. 
This is a ereat improvement upon the old method of plastering, as it will 
bear washing with soap and water. Sulphate of lime is much used for 
statuary. Plaster casts are often taken from persons after death, but with 
the faithful preservation of their lineaments, there is also, in such busts, 
but too accurate a delineation of that last repose, which, however sanctified 
by religious hopes, humanity yet shudders to contemplate. 

691. Sulphate of Magnesia was first obtained from a mineral 
spring, at Epsom, England ; hence its common name, Epsom 
salts. It is less bitter than the sulphate of soda, which it resem- 
bles in taste and medicinal properties. It is sometimes called 
Stidlitz salts, from a village in Bohemia which contains mineral 
springs strongly impregnated with this salt. It exists in sea- 
water, from which it may be obtained by evaporation. It is also 
manufactured from magnesian lime-stones. It is found crystal- 
ized in large quantities, in lime-stone caverns in Kentucky, and 
several other of the Western States. 

692. Sulphate of JUumina exists in nature in a mineral called 
aluminatc. It may be formed by mixing alumina with sulphu- 
ric acid. The pure sulphate is of little importance ; but com- 
bined with sulphate of potassa it forms a double salt of alumine 
and potash ; which is the common alum of commerce. This 
salt has an astringent taste, is soluble in water ; reddens in- 
fusions of purple cabbage slightly ; changes blue infusions from 
the petals of flowers to a green color. 

Exp. Suspend a frame work of string, or wires in a vessel filled with a 
hot, solution of alum, large and beautiful crystals will collect upon the 
frame, and thus may be formed a variety of pretty ornaments, as baskets, 
vases, and flowers. Alum crystals contain half their weight of the water of 
crystalization. When heated, they melt in this water, swelling and froth- 
ing, while the water passes off, leaving anhydrous alum in a white, licht, and 
spongy mass. When heated with sugar, alum forms a compound which in- 
flames spontaneously; it is known as Ho7nberg's pyrophorus. Native soda 
alum is found in South America and in Greece. 

The chemical equivalent of pure sulphate of alumina is slated at 58 ; and 
the composition of alum is as follows; 

Sulphate of potassa, 1 equivalent, =88 

Sulphate of alum, 3 equivalents, (58x3) = 174 
Water, 25 equivalents, (9x25) 225 

Chemical equiv. of Sul. alumina and pot. =487. 

691. Sulphate of magnesia. 

692. Sulphate of alumina. Alum. Exp. Anhydrous alum. Homberg's 
pyrophorus &c. Composition of sulphate of alumina. Law of chemical 
combination illustrated by this salt. Uses of alum, &c. 



SULPHATE OF IRON. 265 

The composition of this salt illustrates an important law of chemical com- 
bination, viz ; that, in the double sulphates, the quantity of oxygen in one 
of the bases, will be proportioned to the quantity of oxygen in the other base. 
Now the oxygen in potassa is, in proportion to the oxygen of alumina, as 1 
to 3 ; therefore, there are 3 equivalents of alumina to 1 of potash in alum ; 
thus each base furnishes to the common stock, an equal amount of oxygen. 

Alum is an important article of commerce, and is employed in medicine 
and the arts ; it is used in dyeing, calico printing, in paper manufactories 
and by tallow chandlers to render their tallow more solid. It is not common 
in nature, but its elements are abundant. Where it is already formed, as 
at Solfaterra near Naples, it is sufficient to lixiviate* the earths, which con- 
tain it, and crystalize the liquor. 

693. General remarks. The sulphates which are formed by 
the union of sulphuric acid with the fixed alkalies and alkaline 
earths, are the most important species of this genus. Those 
sulphates which are formed with oxides having neither earthy 
nor alkaline properties, and therefore commonly called metallic 
oxides, are scarcely less numerous than these oxides themselves, 
since all have some affinity, more or less, for sulphuric acid. But 
it should be remembered, that, in principle, there is no distinction 
between alkaline, earthy, and metallic salts, since all salts (with, 
the exception of those of ammonia and the vegetable bases, which 
we shall hereafter consider,) are composed of acids and metallic 
oxides. Thus potassa and soda are now known to be oxides of 
metals, no less than the oxides of iron and copper ; though the 
two former are usually, called alkalies, and the two latter me- 
tallic oxides. 

694. Sulphate of Iron. Sulphuric acid combines with three 
oxides of iron ; but according to Berzelius there are but the 
proto and the persulphate. He regards the deutosulphate as a 
compound of the two others. The protosulphate, or sulphate of 
the protoxide of iron commonly called copperas, green vitriol, 
&c. may be formed by the action of dilute sulphuric acid on 
metallic iron. Water is decomposed and furnishes oxygen, 
which uniting with the metal forms the protoxide; hydrogen 
escapes with effervescence, and sulphuric acid unites with the 
newly formed oxide. This sulphate is seldom found in nature 
in a solid state; but is often found, in solution, in water flow- 
ing in the neighborhood of mines* 

This salt crystalizes in rhombic prisms, is of a beautiful green color, and 
inky taste. Its color is owing to its water of crystalization of which it 
contains 45 parts in 100 of its weight. When deprived of this water by 

* To leach them, or to form a ley of them. 



693. Most important species in this genus of salts. Salts which are not 
based on metallic oxides. 

694. Number of combinations of sulphuric acid with oxides of Iron. .Fro- 
tosulphate of iron, or copperas, &c. 

23 



266 SULPHATE OF COPPER. 

heat, it becomes of a dirty white color. This salt is useful in the arts, par- 
ticularly in that of dyeing. In combination with nut galls it forms ink. 

Persulphate of iron is formed by the action of nitric acid with the proto- 
sulphate, or by the action of sulphuric acid upon the red oxide of iron, 
slightly moistened with water. It is not crystalizable. 

695. The persulphate (or sulphate of the peroxide of iron) has 1^ an 
equivalent, or 60 parts of sulphuric acid, with 1 equivalent of peroxide of 
iron. This furnishes a striking instance of the acid of a salt being in pro- 
portion to the oxygen of the base ; the more remarkable as the peroxide of 
iron has its half equivalent of oxygen, and we find it requiring an additional 
half equivalent of the acid for its saturation. 

696. Sulphate of manganese appears in transparent crystals 
of a slight rose tint. 

Sulphate of zinc or white vitriol reddens blue vegetable colors, 
though in its composition it is a neutral salt, consisting of one 
equivalent of acid and one of oxide. It is obtained in granular 
masses, resembling sugar ; but by evaporation may be crystal- 
ized in quadrangular prisms. It is employed in medicine, as an 
astringent, and in certain cases as an emetic. 

697. Sulphate of Copper. There is no sulphate of the protoxide 
of copper; for, according to Proust, when this protoxide is 
heated with sulphuric acid, the result is, a solution of the 
deutoxide of copper, and a precipitate of metallic copper, which 
appears as a red powder. — Thenard. The bisulphate of copper 
(sulphate of the deutoxide) is the Hue vitriol of commerce. 

It crystalizes in prisms with an oblique base ; its crystals contain in large 
quantities the water of crystalization, which renders them transparent, and 
gives them a beautiful blue color. Exposed to the air they become slightly 
efflorescent, and are covered with a whitish crust. They fuse easily, in 
their water of crystalization, and become white. This salt has a strong 
metallic taste, is used in medicine as a caustic, and when taken into the 
stomach excites nausea. It is soluble in water, but not in alcohol. It is 
seldom found crystalized in nature ; but, by evaporating the water of cop- 
per mines,* in which this salt exists in solution, the crystalized blue vitriol 
of commerce is obtained. The same substance is also prepared by roasting 
copper pyrites with access of air and moisture, the sulphur is acidified, the 
copper oxidized, and the deuto-sulphate which is formed, is extracted by 
solution and crystalization. 

Anhydrous sulphate of copper consists of 

Peroxide of copper, 1 equiv. =80 
Sulphuric acid, 2 do. =80 

Compound equivalent, =160. 

The crystalized sulphate contains in addition 

10 equivalents of water, =90 

The equiv. of the crystalized sulphate is =250. 

• Copper ore usually contains some sulphur; copper pyrites is the sul- 
phuret of copper. 

695. Persulphate of iron. 

696. Sulphates of manganese and z[nk. 

697. Why is there no sulphate of copper ? Bi-sulphate of copper. Blue 



SALTS. 267 

The sulphate of copper reddens vegetable blue colors ; it is therefore 
called a. super-sulphate, and sometimes a bi-per sulphate. Silliman justly re- 
marks,! " The refinements of a significant nomenclature are sometimes 
embarrassing, requiring frequent changes with the progress of discovery, 
and presenting names which are inconveniently long; they also compel us 
to return occasionally to the old proper names, such as alum, common salt, 
white, green, and blue vitriol." To this remark we would add, that our 
Chemists have undoubtedly gone too far in attempting to introduce technical 
names into common language. Our respect for science would scarcely pre- 
vent a smile should we hear one call for the protoxide of hydrogen combined 
with hydrocarbonous oxide, instead of water and sugar. 

When ammonia is added to a solution of blue vitriol, a pre- 
cipitate appears, of a greenish blue color ; on adding an excess 
of ammonia, this precipitate is dissolved and forms a liquid of 
a beautiful blue color, called celestial blue ; it is the ammoniaret 
of copper. Ammonia affords a valuable test of copper. The 
sulphate of copper is used in the arts to prepare blue cinders used 
in coloring paper, and ScheeWs green. 

698. Sulphites. Salts of this sub-genus are formed by the 
union of sulphurous acid with salifiable bases. They are dis- 
tinguished by a disagreeable taste, and an odor like that of 
burning sulphur. When exposed to air and moisture they 
absorb oxygen, and pass to the state of sulphates. They are 
decomposed by the stronger acids, such as the sulphuric, hydro- 
chloric, &c, effervescence takes place, owing to the escape of 
sulphurous acid, and a sulphate is formed. Nitric acid, by 
yielding oxygen, changes the sulphites into sulphates. 



CHAPTER XXIX. 

SALTS OF THE OXACIDS CONTINUED. 
GENUS II. NITRATES. 

699. The nitrates may be formed by the action of nitric acid 
on metals, or their oxides. In the former case, according to the 
theory of the formation of salts, the metal must first oxidize, 
before it will become a salt. The nitrates are acted upon by 
sulphuric acid, which disengages nitric acid in the form of dense, 

f Elements, Vol. II. p. 282. 



vitriol. Composition of the anhydrous sulphate of copper, and the crystal- 
ized copper. Properties. Chemical names not adapted to common lan- 
guage. Blue vitriol with ammonia. Uses of sulphate of copper in the arts. 

698. Sulphites. 

699. Nitrates. "Which are most readily decomposed ? 



268 NITRATE OF POTASSA. 

white, acid vapors, having the peculiar odor of nitric acid. 
They are all decomposed by heat, giving out oxygen and be- 
coming nitrites. By a strong heat they lose all their acid. 
They deflagrate when heated with charcoal or other combustible 
substances. 

Most of the nitrates are composed of one equivalent of acid, and one of 
a protoxide ; the oxygen of the oxide and acid is, in these cases, in the 
ratio of 1 to 5, because the proportion of oxygen in the protoxide is 1, and 
in the nitric acid 5. The oxides of those metals which have the least affi- 
nity for oxygen, as gold, palladium, &c. part with their oxygen at a low 
temperature, and the nitrates formed with them are easily decomposed, 
while the nitrate of lead and some others, require a red heat for their de- 
composition. 

700. Nitrate of Potassa* nitre, salt petre, &c. exists in great 
quantities, in nature. It is not found in large masses, but dif- 
fused on the surface of the earth, usually in connection with the 
nitrates of lime and magnesia, in places where animal substances 
have suffered decomposition. Efflorescences of this salt, resem- 
bling mould, are found upon the damp walls of old cellars and 
subterranean buildings, especially when these walls are covered 
with lime mortar. Nitre is manufactured by lixiviating the 
substances in which it is contained, and evaporating the solution. 
In the East Indies it is abundant as a natural production ; and 
large quantities are imported from thence into Great Britain 
and the United States. In Italy and Spain it is found in the 
dust of the roads ; and it is common in the grounds near Lima 
in South America. It exists in some plants, as the hemlock, 
sunflower, tobacco, &c. 

701. Properties. It is a white substance with a cool and sharp taste, and 
deflagrates when thrown upon burning charcoal. With heat it suffers the 
ignevis fusion, as it contains no water of crystalization, though its crystals 
are not quite free from some water of interposition, or water lodged mechani- 
cally in their interstices, instead of being chemically combined with their 
particles. Nitre is used in chemistry as a deoxidizing agent, and to obtain 
oxygen,f and nitric and sulphuric acids. It is useful in medicine on account 
of its cooling properties. It is an antiseptic, and is used in the salting of 
meat, to which it imparts a fine color, rendering the fibre both tender and 

* The nitre of the scriptures is the carbonate of soda, called in Greek, 
natron, and in Latin nitrum. Thus in Prov. 25 : 20, " as vinegar upon 
nitre, so is he that singeth songs to a heavy heart." Here the effervescence 
or disturbance caused by the action of the acid vinegar upon the carbonate 
is evidently alluded to. In Jeremiah 11 : 22, we read of washing with 
nitre ; the cleansing or detergent property of the carbonate of soda must be 
referred to. 

f Oxygen being driven from nitre by heat, may be collected over the 
pneumatic cistern. 

700. Nitrate of potassa as found in nature. Manufacture of nitre. In 
what countries most abundant. Exists in plants. 

701. Properties. Action with heat. Uses. Tests. Action with water. 



NITRATE OF SILVER. 269 

compact. It can be known by its deflagrating on burning coals, and by the 
disengagement of the fumes of nitric acid, when tested with sulphuric acid. 
Owing to its rapid combination with water, it forms with ice a valuable 
freezing mixture. 

702. Its action with combustibles constitutes its efficacy as an ingredient 
in gun powder, which is a mixture of 75 parts of nitre, 10 of sulphur, and 15 
of charcoal. These are the usual proportions, but they are sometimes varied. 
The composition of gun powder was discovered by Roger Bacon, a friar, in 
the fourteenth century. It is supposed that the Chinese were previously 
acquainted with it. It was first used by the English at the battle of Agin- 
court in 1415. Gun powder is merely a mechanical mixture, as at common 
temperatures no chemical action takes place among its parts. But when 
heated, the oxygen which the nitre yields so readily and abundantly, acts 
on the carbon and sulphur, producing with the latter a rapid and violent 
combustion, while the former yields a large proportion of elastic vapor. The 
volume of gas produced from powder at the moment of explosion, is said to 
be 1000 times greater than that of the solid powder. As each additional 
volume of gaa exerts a force equal to that of the atmosphere, which is 15 
pounds to the square inch, the force of this elastic vapor will be 1000X15 
= 15,000 pounds on a square inch ; this according to calculation will project 
a bullet with a speed of 2000 feet in a second. The products of the detona- 
tion of gunpowder, are both gaseous and solid ; the former consisting of mix- 
tures of nitrogen, nitric oxide, carbonic acid, sulphuretted and carburetted 
hydrogen and ammonia. The solid products jtte some sulphate, and sulphu- 
ret of potassa, carbonate of potassa and charcoal. 

Various fulminating powders are made with nitre, some of which produce 
a more powerful detonation than gun powder. 

703. Nitrate of Silver is obtained by dissolving silver in nitric 
acid. Cast in small moulds, it forms the lunar caustic* or lapis 
infernalis of medicine. It is highly corrosive, and changes the 
skin, first yellow, and then black on exposure to the air, (owing 
to the decomposition of the oxide of silver.) In a very dilute 
state it is used, with other ingredients, for staining the hair 
black, and for indelible ink, used in marking linen. 

An imposition has heretofore been practiced by the venders of the mark- 
ing ink, by selling at a great price, a vial of what they call solution ; which is 
merely a solution of pearlash and water. The article to be marked, is wet 
with this solution, and then dried. The ink is, a colorless liquid, (unless 
it contains a small portion of India ink;) but the alkali of the pearlash, 
seizes the nitric acid, and forms nitrate of potash ; the oxide of silver being 
liberated, is precipitated among the fibres of the linen. Exposure to light, 
partially decomposes the oxide of silver, and the letters become black. 
When a white garment has been accidently stained with this ink, the spot 
may be removed by steeping in diluted nitric acid. 

* Lunar is derived from the ancient name of silver, caustic, from its agency 
in destroying animal texture. The name lapis infernalis, or infernal stone, 
was given in allusion to its strong burning property. 

702. Gunpowder. Its composition. Discovery. Cause of its combusti- 
ble nature. Cause of its explosive property. Force. Products of its de- 
tonation. Fulminating powders. 

703. Nitrate of silver, how formed ? Lunar caustic. Indelible ink. 
Mode of marking with this ink. Exposure to light. 

23* 



270 



CHLORATES. 



704. Nitrites and Hyponitrites. 

When nitrous acid is brought in contact with a salifiable base, 
the result is a nitrite, and under certain circumstances a hypo- 
nitrite. Nitrous acid does not appear to be susceptible of a 
permanent union with salifiable bases. By exposing the nitrates 
to a red heat, oxygen is given off and nitrites are formed ; but 
by exposure to the air, the latter absorb oxygen, and again be- 
come nitrates. The hyponitrites, contain a less portion of oxygen 
than the nitrites. They are decomposed by water even at the 
ordinary temperature. 



genus in.- 



CHLORATES. 



705. These salts (formerly called Hyperoxy muriates,) are form- 
ed by the combination of bases with chloric acid. They defla- 
grate with even greater violence than the nitrates, yielding oxygen 
so readily, that the slightest agitation will produce their explosion. 
They are soluble in water, and decomposed by heat, giving off 
oxygen, and becoming metallic chlorides. Most of the chlorates 
are composed of one equivalent of chloric acid, and one of a pro- 
toxide, it follows, therefore, that the oxygen of the latter, to that 
of the former, is in the raffft) of 1 to 5, (chloric acid having 5 pro- 
portions of oxygen.) None of the chlorates are found native. 
They were discovered by Berthollet, in 1786. 

706. Chlorate of potassa, (hyperoxymuriate of potash) is the 
most important species of the chlorates. 

Exp. It may be formed by passing a stream of chlorine gas, (Fig. 119,) 

Fig. 119. 




704. Nitrites. Hyponitrites. 

705. Former name of chlorates. Formation and character. Decompo- 



sition. 



706. Chlorate of potassa. How formed ? Exp. Rationale of the process. 



CHLORATE OF POTASSA. 



271 



through a solution of caustic potash in Woulfe's bottles, or by saturating 
the gas with a solution of potash. A, represents the outer one of three 
jars,"containing solution of the sulphate of potash ; peroxide of manganese 
being put into a retort C, and some hydrochloric acid added to it, chlorine gas 
is disengaged, and passes to the globe B, from whence it proceeds into the 
inner jar. If it be not all absorbed by the liquid in this jar, the superfluous 
gas will escape into the next jar, and so on, until all the liquid is saturated ; 
any gas which remains in excess, is conducted off by the pipe P, and receiv- 
ed in an inverted bell glass. E is a pipe which, when extended, may still 
further serve for conducting off the superfluous gas, into a suitable receiver. 
In this operation, it is supposed that one part of the potassa is deoxidized, 
and the reduced metal uniting with chlorine forms the chloride of the po- 
tassium, which is in solution ; and that the oxygen of the potash unites to 
another portion of the chlorine, producing chloric acid, which, combining 
with the undecomposed potassa, forms the chlorate of potassa. 

Fig. 120. 707. Dr. Hare contrived the ap- 

paratus here represented (Fig. 120,) 
for the purpose of separating the 
solution of chlorate of potassa from 
potassa and siliceous earth. A large 
vessel of sheet tin was fitted to a 
tin funnel, to support a glass filter- 
ing funnel, and furnished with an 
aperture which serves the purpose 
of a chimney, by conducting off the 
smoke of the Argand lamp below. 
This lamp keeps the water hot, with 
which the tin vessel is filled. The 
hot water thus surrounding the so- 
lution as it filters, prevents its cool- 
ing. A coarse fibrous paper for a 
filter, is placed within the funnel ; 
the filtering solution of chlorate of 
potassa, is received in the decanting 
jar beneath. On being kept undis- 
turbed, the salt crystalizes in beau- 
tiful white, rhomboidal scales, re- 
sembling mother of pearl. Their 
taste is cool, but bitter and nauseous. The crystals are anhydrous, and 
suffer the igneous fusion, below red heat ; at a higher temperature they 
give off oxygen, with boiling and effervescence, and become chloride of po- 
tassium. 

708. Properties. Chlorate of potassa yields a large propor- 
tion of pure oxygen gas. For this reason it acts powerfully on 
combustibles, readily inflaming them and producing violent 
detonation. Two parts of chlorate of potassa mixed with one 
of sulphur, and put into a paper, will explode with great violence 
on being struck with a hammer. When rubbed in a mortar 
with phosphorus or charcoal, a loud detonation and jets of fire 
are produced. 




707. Dr. Hare's apparatus for purifying chlorate of soda, &c. 
of ehlorate of potassa. Action of heat upon the crystals. 

708. Properties. Exp. 



Crystals 




272 BEOMATES. 

Exp. If a small portion of phosphorus covered by chlorate 
of potassa (Fig. 121,) be placed in a glass which i3then fill- 
ed with water and sulphuric or nitric acid, poured in through 
a long glass funnel, the mixture is inflamed, and burns with 
great brilliancy, with a series of detonations. Sugar mixed 
with chlorate of potash, deflagrates with the addition of a 
small quantity of sulphuric acid. 

709. Chlorate of potassa is used in the arts, for fire- 
matches, and attempts have been made to introduce it as an 
ingredient in gun-powder ; but, though it produces a ptfwder 
of greater impelling force than that which is commonly used, 
it inflames so easily by slight friction, or shocks, that its 
manufacture and use are very dangerous, and prevent its being employed 
for this purpose. 
It is composed of 

Chloric acid 1 equivalent— 76 
Oxide of pot. 1 do. =48 

Chemical equiv., therefore=124 

Its ultimate compounds being 6 proportionals of oxygen, 5 in the acid and 

1 in the alkali, 6x8 =48 

1 proportion of chlorine =36 

1 do potassium =40 

Compound chemical equiv. =124 

710. Perchlorates or oxygenated chlorates, are formed by the 
union of perchloric acid with salifiable bases. These salts dis- 
covered by Count Stadion, are little known. 

GENUS IV. IODATES. 

711. The iodates are produced, either by combining iodic 
acid directly with bases, or by double decomposition. The 
composition of iodic acid being similar to chloric acid, in re- 
spect to the quantity of oxygen, the iodates, like the chlorates, 
contain oxygen in the oxide and acid in the proportion of 1 
to 5. Like the chlorates, they form deflagrating mixtures with 
sulphur, and other inflammables. Most of the acids decompose 
the iodates, by attracting the oxygen from iodic acid. The 
iodate of potassa is the most important species of this genus. 

GENUS V. BROMATES. 

712. Like chlorates and iodates, the proportion of the oxide 
to the acid in the bromates, is in the ratio of 1 to 5, bromic acid 

709. Uses of chlorate of potassa. Cause which prevents its being used 
in gun-powder. Composition. 

710. perchlorates. 

711. Remarks on the genus, iodates. 

712. Bromates. 



CHROMATES. 273 

containing 5 proportions of oxygen. The properties of bromates 
appear to be analogous to those of chlorates, and iodates. 

GENUS VI. PHOSPHATES. 

713. These salts are not decomposable by heat, but melt at a 
high temperature. They are extensively diffused in nature. 
The phosphate of lime is most abundant, often forming an impor- 
tant constituent of mountain masses, and existing largely in 
animal bones. There are phosphates with excess of base called 
alkaline phosphates, neutral phosphates , acidulated phosphates and 
acid phosphates. 

714. Phosphites are a combination of phosphorus acid with 
salifiable bases. When exposed to heat, they disengage phos- 
phuretted hydrogen, and a little phosphorus, while a phosphate 
colored by the oxide of phosphorus remains. When thrown 
upon burning coals, they produce a yellow flame. Hypophos- 
phites are combinations of hypophosphorus acid with bases. 
They are too soluble to be crystalized. 

GENUS VII. ARSENIATES. 

715. Salts composed of arsenic acid with bases are called 
arseniates. 

Arsenites are combinations of arsenious acid with bases. 
They are distinguished from the arseniates by a green precipi- 
tate with sulphate of copper, while the arseniates form with the 
same compound a bluish white, precipitate. The arsenite of cop- 
per is Scheele's green. The arsenite of potassa is known in 
medicine as Fowler's solution. 

GENUS VIII. CHROMATES. 

716. The salts which result from the union of chromic acid 
with salifiable bases, are all colored ; yellow and red are the 
prevailing colors, the latter appearing when there is an excess 
of acid. The chromate of lead is a brilliant yellow, known in 
the arts as chrome yellow, it is of a beautiful pink in the state 
of a subsalt ; chromate of lime is yellow, and chromate of potassa, 
lemon color ; potassa combines with an excess of chromic acid, 
in which case the salt is of intense orange color ; chromate of 
silver is of a rich crimson color ; chromate of copper, apple green. 

713. Phosphates. 

714. Phosphites. Hypophosphites. 
715 Arseniates. Arsenites. 

716. Character of the chromates. Chromate of lead. Chromate of lime. 
Chromate of potassa, &c. Chromates of silver and copper. 



274 CARBONATES. 

GENUS IX. BORATES. 

717. Boracic acid is reckoned among the weak acids ; its 
salts are therefore readily decomposed by the greater attraction 
of other acids for their bases. The Borates dissolve in alcohol, 
and burn with a green flame. Biborate of soda is imported from 
the East Indies in a crude state under the name of tincal. This 
is purified in the substance known in the arts as borax. When 
exposed to heat its crystals lose their water of crystalization, 
and become fused, forming a vitreous substance called glass of 
borax. It is used in chemistry for the preparation of boracic 
acid ; and in glass making and pottery, as a flux. 

GENUS X. CARBONATES. 

718. Properties. These salts effervesce with most acids, owing 
to the rapid disengagement of carbonic acid, for which the bases 
have but a feeble affinity. The carbonates of the alkalies have an 
alkaline taste, and change to green the vegetable blue colors ; 
those of the earths are insoluble but become soluble with an 
excess of carbonic acid. Many of the carbonates are found in 
nature. 

719. Carbonate of pot ass a is not found in nature, but is ob- 
tained by lixiviating vegetable ashes, and evaporating the solu- 
tion to dryness. Pearlash or saleratus differs from the crude 
carbonate of potash, only in being freed from impure matter. 
It is an article much used in domestic operations. 

Its action with flour in raising bread, biscuits, Sec. depends on the readi- 
ness with which it disengages carbonic acid, which becoming entangled 
among the glutinous particles of the paste, tends to make a light and spongy 
mass. On its alkaline properties depends its utility in neutralizing the sour- 
ness produced by suffering the dough to regain unbaked, until the vinous 
fermentation changes to the acetous. Some housewives prefer to let their 
dough thus sour, as, by adding pearlash, bread and biscuit are rendered 
more spongy and tender, while the acidity may be wholly corrected. But 
this process, unless carefully conducted, will give to the bread a darker hue, 
and the peculiar taste of pearlash. With a little attention, however, very 
delicate and palatable biscuit may be made without yeast, simply by the ac- 
tion of pearlash and sour cream, or milk mixed and kneaded with the flour, 
and baked immediately. The common pearlash is uncrystalized, and anhy- 
drous. It exists in white porous masses, potash is harder and of a darker 
color. 



717. Character of the borates. Biborate of soda. Crystals. Glass of 
borax. 

718. Character of the carbonates. 

719. Carbonate bfpotassa, how formed ? Pearlash. Its use in domestic 
economy. 



CARBONATES. 275 

720. Carbonate of soda, is obtained by lixiviating the ashes of 
marine plants. The soda of commerce is an impure carbonate, 
which may be purified by heat. Though alkaline, it is not 
highly caustic. Its solution forms beautiful crystals composed 
of two quadrilateral pyramids. They contain 10 equivalents of 
of water, with 1 of carbonic acid and 1 of soda ; or acid 1 equiv. 
=22 added to do. soda, 32, added to 10 do. water, 90=144 
which is the equivalent of crystalized carbonate of soda. 

Bicarbonate of soda is, in its composition analogous to the bicarbonate of 
potassa. A sesqui carbonate is said to exist native on the banks of soda lakes 
in Africa ; this in commerce is called trona. The best variety of the carbo- 
nate of soda which is known in commerce is called barilla ; an inferior kind 
is called kelp. These substances are much used in the manufacture of 
glass, soap, in dyeing, bleaching, and in the preparation of artificial soda 
water. 

721. Carbonate of ammonia, commonly called volatile salts of 
hartshorn ; is considered as a sesqui* carbonate, consisting of 
1 equivalent of ammonia, with 1| carbonic acid. It is prepared 
by heating hydrochlorate of ammonia with carbonate of lime ; 
double decomposition ensues, hydrochlorate of lime remains in 
the retort, and the sesqui carbonate of ammonia sublimes. 

This salt is the white substance contained in the hartshorn smelling bot- 
tles. Its odor is volatile, pungent and stimulating lo the nerves. It pro- 
duces the alkaline effects on blue vegetable colors,* alkaline earths attract 
its acid and liberate ammonia, while the acids attract ammonia and liberate 
the carbonic acid gas with effervescence. The proper carbonate of ammonia 
or that with 1 equivalent of acid and 1 of the base, is formed by mingling 
carbonic acid gas over mercury, with twice its volume of ammonia. 

Bicarbonate of Ammonia is prepared by saturating a solution, 
of the carbonate with carbonic acid gas. The common hartshorn 
or sesqui carbonate, when exposed to the air, loses ammonia 
and gains carbonic acid, and appears to be converted into a bi- 
carbonate, becoming almost inodorous and tasteless. 

This salt is composed wholly of gases in a condensed state ; the acid con- 
sisting of carbon and oxygen, the base of hydrogen and nitrogen ; or 
Acid, 1 equiv. carbon 6 added to 2 equiv. oxygen 16=22 
Base, 1 equiv. nitrogen 14 added to 3 equiv. hydrogen 3=17 

The chemical equivalent of this salt is, therefore, 39 
As there are two equivalents of acid and one of base, the proportions are, 
carbonic acid 44 added to ammonia 17=61. The carbonate of ammonia is 
a most valuable medicine. It is much used in chemistry as are-agent, and, 
diluted with water, has its useful applications in domestic economy, in re- 
moving spots of oil or grease from cloth, &c. 

* The term sesqui signifies one and a half. 

720. From what plants is the carbonate of soda obtained ? Soda of com- 
merce. Crystals. Composition of the crystals. Bicarbonate. Sesqui-car- 
bonate. Barilla and kelp. Their uses. 

721. Carbonate of ammonia. Composition. Preparation. Smelling bot- 
tles. Properties. The proper carbonate. Bicarbonate. Composition. Uses 
of carbonate of ammonia. 



276 CARBONATES. 

722. Carbonate of baryta may be prepared by double decompo- 
sition, by mixing a soluble salt of baryta with any of the alka- 
line carbonates. It is found native : is an insoluble salt, and of 
great use in chemistry for preparing the other salts of baryta. 
It is not readily dissolved by heat. 

723. Carbonate of lime is an insoluble compound of lime, ex- 
isting abundantly in nature, in the form of lime-stone, marble, 
chalk, stalagmites, spar, &c. It is decomposible by fire, and by 
most of the acids, with effervescence. It is used in chemistry 
for obtaining pure lime, and carbonic acid, and in the arts for 
building and statuary. It is much used as a manure for soils, 
both in the form of lime and carbonate of lime. 

The advantage of burning it for this purpose appears to be of no other 
use than to destroy cohesion, so that it may be easily scattered among the 
soil ; for quick lime soon becomes a carbonate by absorbing carbonic acid 
from the atmosphere. It was discovered by Dr. Black, in 1756, that lime 
acquired its caustic properties by the loss of carbonic acid. Though insolu- 
ble in water, carbonate of lime dissolves by an excess of carbonic acid : for 
this reason the spring water oflime stone countries is impregnated with this 
salt which is found deposited upon the bottom and sides of tea kettles, in 
which such water is boiled. 

724. Carbonate of magnesia is prepared by decomposing sul- 
phate of magnesia with carbonate of potassa. It is not found pure 
in nature, being mixed with lime, silex, &c. Calcined magnesia 
is the carbonate deprived of its magnesia by heat. 

Carbonate of iron exists in nature in masses and veins. It is 
contained in most mineral springs, being held in solution by 
percarbonic acid. 

It may be prepared by decomposing the sulphate of iron by a solution of 
carbonate of soda or potassa. The precipitate of carbonate of iron readily 
attracts oxygen from the atmosphere, and the protoxide of iron, becoming 
a peroxide, parts with carbonic acid, which does not form with it a definite 
compound. Thus the carbonate of iron known in medicine, is chiefly the 
peroxide, distinguished by its red color. 

Carbonate of copper exists in nature as a beautiful light green mineral, 
called malachite, which is a carbonate of the peroxide of copper. It may be 
prepared by adding carbonate of potassa to nitrate or sulphate of copper. 
In an impure state it constitutes the blue pigment known as verditer. 

Carbonate of lead, whitelead, or ceruse. This substance, so much used in 
the arts, is rarely found in nature. It is manufactured by introducing a 
current of carbonic acid gas into a solution of the acetate of lead. Another 
method is to expose thin plates of sheet lead to the vapor of vinegar, which, 
by its acid fumes, fix'st oxidizes the lead, and then changes it to a carbonate. 

722. Carbonate of baryta. 

723. Carbonate of lime, as found in nature. Decomposition. Uses. The 
utility of burning it for manure. Dr Black's discovery. Solution of car- 
bonate of lime. 

724. Carbonate of magnesia. Of iron, lime, copper and lead. 



HYDROCHLORATES. 277 

CHAPTER XXX. 

ORDER II. SALTS OF THE HYDRACIDS OR HYDROSALTS. 

725. The term hydracid is somewhat exceptionable, as it may- 
lead to the error that hydrogen performs the same office in the 
hydracid, as oxygen does in the oxacid ; whereas, it is the 
element with which hydrogen is united in these acids, that is 
in reality, the acidifying principle, and analogous to oxygen ; 
thus chlorine and iodine, like oxygen, are supporters of com- 
bustion, while hydrogen is a combustible body. Like oxygen, 
chlorine and iodine on the decomposition of hydrochloric and 
iodic acids by galvanism go to the positive pole, being, like ox- 
ygen, negative in relation to hydrogen. 

The acids in which hydrogen is a constituent element, and 
which form distinct genera of salts with different bases, are the 
following : Hydrochloric, (muriatic acid) Hydriodic, Hydrobromic, 
Hydrofluoric, Hydrosulphuric, (sulphuretted hydrogen,) Hydro' 
cyanic, (prussic acid.) 

GENUS I. HYDROCHLORATES. 

726. These salts are composed of hydrochloric acid, and me- 
tallic oxides. The name, muriatic acid, was first given to the 
hydrochloric, on the supposition that it was composed of oxygen, 
and a base called muriatum ; after the discovery of chlorine, 
and the consequent change of opinion with respect to the nature 
of muriatic acid, the name hydrochloric, was given in conformity 
with the principles, of the new nomenclature. Yet the name 
muriatic acid, had become so well established, and its com- 
pounds, the muriates and oxymuriates, so well known by the- 
names, that custom has, in a measure, prevailed over the man 
dates of science, even among chemists themselves. But expla- 
nations respecting the nature of these compounds and their 
changes according to theories now established, are more intel- 
ligible by the new nomenclature. For instance, when hydrogen 
or chlorine are said to be disengaged by the decomposition of a 
muriate, the nature of the process will not so readily be compre- 
hended as if the term hydrochlorate had been used. 

725. Difference in the nature of the office performed by the hydrogen and 
oxygen of these respective acids in the formation of salts. Number of hy- 
dracids. 

726. Cause of the change of the name muriatic acid, to that of hydrochlo- 
ric. Why may chemical changes be better understood by using the proper 
chemical terms ? 

24. 



278 HYDRIODATES. 

727. Hydrochlorates are intimately related to the chlorides, as in desic- 
cation, (drying) and crystalization the hydrogen of the hydrochloric acid 
unites with the oxygen of the oxide forming water, and leaving the chlorine 
united to the metallic base of the oxygen, in other words, the hydrochlorale 
has become a chloride. On the other hand, when the chlorides are dissolv- 
ed in water, the chlorine unites with the hydrogen, and the metal with the 
oxygen of the water, aud the newly formed hydrochloric acid, and metallic 
oxide combine to form a hydrochlorate. Thus dry common salt is chloride 
of sodium, but, dissolved in water, it is chlorate of soda. Dry hydrochlo- 
rates or muriates, except that of ammonia, are mostly considered as chlo- 
rides. 

Properties. The hydrochlorates differ from all other salts by forming the 
white insoluble chloride of silver, when mixed with the nitrate of silver, and 
by being decomposed at the common temperature by sulphuric acid, with 
effervescence, and disengagement of white pungent fumes, characteristic of 
hydrochloric acid. They differ greatly from the nitrates in being little af- 
fected by charcoal, sulphur and other combustibles. They melt and volati- 
lize by heat. They are soluble in water. The hydrochlorates which are 
found in nature are, ammonia, soda, Jime, potassa and magnesia. 

728. Hydrochlorate of ammonia, (the salammoniac of commerce) 
may be prepared by decomposing sulphate of ammonia, with 
the hydrochlorate of soda. The two gases ammonia and hydro- 
chloric acid exchange bases, and unite, forming the solid hydro- 
chlorate of ammonia, which is obtained pure by sublimation. 

Hydrochlorate of soda, is the chief constituent of sea-water; 
it exists only in solution, for when evaporated it becomes chlo- 
ride of sodium. Hydrochlorate of potassa exists in solution in 
mineral springs. Hydrochlorate of baryta is an important re- 
agent in chemistry. Hydrochlorate, of lime exists in mineral 
springs, and often gives common spring water the property 
called hardness, which is indicated by its not combining well 
with soap. Hydrochlorate of magnesia is abundant in sea-water, 
and often exists in mineral springs. When hydrochlorate of 
soda is separated from sea-water by crystalization, a liquid 
remains called bittern, consisting mostly of hydrochlorate of 
magnesia. 

GENUS II. HYDRIODATES. 

729. They are formed by the action of hydriodic acid with 
alkaline earths and metallic oxides j and are supposed to exist 
only in solution. In drying, the hydrogen of the acid, unites 
with the oxygen of the oxide forming water j iodic acid then 
unites with the metal, and an iodide remains. Hydriodic acid 

727. Connection of the hydrochlorates and chlorides. Peculiar proper- 
ties of the hydrochlorates. 

728. Hydrochlorate of ammonia. Hydrochlorates of soda, potassa, baryta, 
lime, and magnesia. 



me, anu magnesia. 
729. Remarks upon the hydriodates. 



HYDROSULPHURETS. 279 

does not unite with all the metallic oxides ; it forms salts with 
the alkalies and alkaline earths, and with the oxides of zinc, 
iron, and manganese. The hydriodates of potassa and soda are 
the only salts of this genus which are known to exist in nature. 
They are formed in the water of mineral and salt springs, in 
sea-water, sea-weed, the sponge and oyster, and in some 
other mineral, vegetable and animal substances. 

730. Hydriodate of potassa is more known than any of the salts of this 
genus. It may be prepared by adding hydriodic acid to potassa. On being 
crystalized, the oxygen of the potassa unites with the hydrogen of the acid 
to form water which evaporates, while the iodic acid unites with the po- 
tassium and a solid iodide remains. 

GENUS III. HYDROFLUATES. 

731. They are formed of hydrofluoric acid united with bases. 
The nature of the acid, (see § 298,) is somewhat doubtful. It 
was formerly supposed to consist of oxygen and fluorine ; but 
is now considered as a hydracid. The analogies of this acid 
with the hydrochloric, are in some respects remarkable j and 
these analogies extend to the salts of the two acids. Thus 
when the hydrofluates are evaporated to dryness, they become 

fluorides ', when the latter dissolve in water, they are hydrofluates. 
Though the hydrofluates give the alkaline test with vegetable colors, they 
are, according to Berzelius and Thenard, neutral salts ; that is, composed 
of one equivalent of the acid with one of the base. It is not certain that 
they exist in nature, though the topaz has been called a double hydrojluate of 
silica and alumina; and some other rare minerals have been considered as 
composed of hydrofluoric acids united to metallic oxides. But these com- 
pounds are now regarded as fluorides. Fluor spar was known in chemistry 
as fluate of lime, when its acid was supposed to consist, in part, of oxygen ; 
but it is now regarded as a fluoride of calcium. 

732. Hydrojluate of potassa. Two definite compounds of hydrofluoric acid 
and potassa may be formed. The neutral hydrojluate, consisting of one 
equivalent, and the bihydrojluate , consisting of two equivalents of the acid 
to one of the base. The neutral hydrofluate seems improperly named, since 
it possesses alkaline properties ; the bihydrofluate gives the acid test with 
vegetable colors. The hydrofluoric acid forms also, with soda and ammonia, 
both neutral and acid salts. 

GENUS IV. HYDROSULPHURETS OR HYDROSULPHATES. 

733. The term hydrosulphuric acid, which is generally used by 

730. Hydriodate of potassa. 

731. Remarks upon the hydrofluates. Opinion of Berzelius and Thenard. 
Fluor Spar. 

732. Hydrofluate of potassa. 

733. Synonyme of hydrosulphuric acid. Name of the salts of this acid. 
Properties of the salts. Result of this decomposition. 



280 



HYDUOSULPHATE?,. 



the French Chemists to designate the acid composed of hydrogen 
and sulphur, is more expressive of its composition than the name 
sulphuretted hydrogen. In the one case, the salts formed with the 
acid would be properly called, hydrosulphates ; in the other hydro- 
sulphurets. This acid seems not capable of combining with 
the oxides of many of the proper metals, but forms with the 
alkaline earths, soluble salts, which have an acid and bitter taste, 
and disagreeable odor. 

The composition of the hydrosulphates is such thai if the hydrosulphuric 
acid and the oxide mutually decompose each other, the result is, water and 
a metallic sulphuret corresponding to the degree of oxygen contained in the 
oxide ; thus a protoxide will produce a protosulphuret, and a deutoxide, a 
deutosulphuret. 

734. Hydrosulphuret of ammonia is formed in nature by the decomposition 
of animal substances. It is obtained in the laboratory by combining am- 
moniacal gas with sulphuretted hydrogen gas at a very low temperature ; 
for this purpose, the gases are often mixed in a glass globe surrounded by 
ice; the salt will be deposited in the form of white scales. 

735. The hydrosulphates of potassa, soda, baryta, strontia, lime and magne- 
sia may be obtained directly, by causing a current of hydrogen gas to pass 
into solutions of these bases in water. For this purpose, an apparatus like 
that represented in figure 122 is used. 

Fig. 122. 




The matrass (Fig. 122,) placed over a furnace contains sulphuret of anti- 
mony, the first flask water, to wash the gas, and the third flask contains a 
solution of soda ; more flasks may be added, containing solutions of other 
alkalies or earths. Hydrochloric acid is poured through the branching tube 
upon the sulphuret of antimony, and a gentle heat applied ; hydrochlorate 
of the protoxide of antimony is formed in the matrass, while the hydrosul- 
phuric acid is disengaged.* 

* Thenard " Traite de Chimie." 



734. Hydrosulphuret of ammonia. 

735. Hydrosulphates of potassa, soda, &c. 
salts by means of a current of hydrogen. 



Process for preparing these 



HYDR0FERR0CYANATE3. 



281 



Fig. 123. 



I 



736. Bisulphuretted hydrogen, unites with alkalies 
and alkaline earths forming salts, called sulphuretted 
hydrosulphurets. They absorh oxygen rapidly from 
the air and are used in eudiometry. Figure 123, re- 
presents the eudiometer of Dr. Hope. It consists of 
a graduated glass tube, sealed at one end, and at the 
other fitted, into the month of a tubulated glass bot- 
tle, so as to be air-tight. The tube is filled with 
air, the bottle, with the liquid sulphuretted hydro- 
sulphuret. The tube being inverted the air is made 
to pass into the bottle ; the mixture is agitated, and 
time allowed for the absorption to be completed. 
The oxygen gas absorbed is replaced by water. The 
graduation being inspected, the deficit produced by 
the absorption of oxygen is thus ascertained. 

GENUS V. HYDROCYANATES OR PRUSSIATES, 



737. Are formed by combining hydro- 
cyanic acid (prussic acid) with bases. They 
are distinguished by the formation of a deep- 
blue precipitate with salts of the peroxide 
of iron. With salts of the protoxide they 
give an orange colored precipitate, chang- 
ing in the air to green and blue. 
Hydrocyanate of potassa may be formed directly, by the union of hydro- 
cyanic acid with potassa ; or by the decomposition of water by cyanuret of 
potassium ; in the latter case the oxygen of the water forms an oxide with 
potassium, the hydrogen forming hydrocyanic acid with cyanogen. The 
acid and oxide combined form the salt. Thus the cyanuret of potassium can 
only exist in the dry state, as when dissolved in water it becomes a hydro- 
cyanate. 

The cyanurets of the other alkaline and earthy bases also become hydro- 
cyanates when in solution ; the phenomenon being analogous to that attend- 
ing similar changes in the chlorides, iodides, bromides and fluorides. On 
the other hand, the hydrocyanates, when evaporated become cyanurets, 
parting with hydrogen from the acids, and oxygen from the oxides which 
unite to form water. 




GENUS VI. HYDROFERROCYANATES, 

738. Are sometimes called triple prussiates, ferroprussiatejs, 
?mdferrocyanates. Hydroferrocyanic acid, consists of hydrogen, 
iron and cyanogen. It unites with oxides in the same manner 
as the other hydracids, the hydrogen of the acid being in the 
exact proportion to form water with the oxygen of the oxide. 



736. Bisulphuretted hydrogen. Dr. Hope's eudiometer. 

737. Characteristics of the hydrocyanates. Hydrocyanate of potassa. 
Change of cyanurets by solution. Evaporation of hydrocyanates. 

738. Characteristics of the hydroferrocvanates. 

24* 



282 HALOID SALTS. 

It forms soluble salts with the alkalies and alkaline compounds. 
When evaporated by heat, the hydrogen of the acid goes off 
with the oxygen of the oxide in aqueous vapor, and a ferrocyan- 
uret remains. 

739. Hydroferrocyanate of potassa (triple prussiate of po- 
tassa) is prepared by digesting potassa with pure ferrocyanate 
of the peroxide of iron, (prussian blue,) which last parts with its 
acid, and thereby neutralizes the potassa. It is also formed in 
the manufacture of prussian blue, when the blood, hoofs and 
horns of animals are calcined with potassa and iron. It appears 
in the forms of large, transparent, lemon colored crystals. The 
crystalized salts consist of cyan. 3. potassium 2. iron 1. Hyd., 
3. and Ox., 3 equivalents of each. 

740. Hydroferrocyanate of the peroxide of iron is the basis of prussian-blue. 
It is formed by mixing the hydroferro cyanate of potassa, with the peroxide 
of iron ; the precipitate is of a deep blue color. The prussian blue is pre- 
pared by heating animal substances, with potassa and a salt of iron in a 
large iron crucible. Carbon and nitrogen arising from the decomposition 
of the animal matter form cyanogen, which, uniting with disengaged hydro- 
gen and a portion of iron, forms hydroferrocyanic acid. The acid now com- 
bining with iron and potassa form? a salt with a double base, which may be 
called a hydroferrocyanate of iron and potassa. 

ORDER III. HALOID SALTS. 

Some late chemists have introduced an order of salts having for 
one or both of its constituents a compound analogous to sea-salt ; 
the haloid* acids generally belong to electro-negative elements, and 
the haloid bases to the electro-positive metals. For example, the 
bichloride of mercury is called a haloid acid; its combination 
with metals forms salts, called Hydrargo] — chlorides. The 
perchloride of gold forms with metals aurochlorides. 

SULPHOSALTS. 

These are double salts as the oxy-saltsare double oxides, they 
are often called double sulphurets, among the genera of this 
order as the Hydrosulphurets, Hydrosulphocyanurets i Carbo- 
sulphurets, &c. 

* From hale, sea-salt, and eidos, appearance. 

f From the Latin name of mercury hydrargyrum. 

739. Hydroferrocyanate of potassa. 

740. Hydroferrocyanate of the peroxide of iron. Prussian blue. Haloid 
salts. Sulpho salts. 



CONCLUDING REMARKS. 283 



CONCLUDING REMARKS. 

741. We have now completed an outline of inorganic Chemistry. In a 
subject embracing such a vast variety of combinations, and susceptible of 
so much amplification, we have found it difficult to keep within the boun- 
dary of a simple elementary course of instruction. Yet believing that a few 
principles well understood are of more advantage to the student, than a 
mass of unconnected facts, we have endeavored to bring into bold relief the 
general laws of chemical science, and our choice of facts has often been di- 
rected by this view, rather than by their individual importance. For the 
same reason we have been more careful to explain the rationale of the 
changes described, than to enter into minute details of manipulations.* We 
have not attempted to follow the elementary substances through all their 
metamorphoses in the various arts and manufactures, but have sought ex- 
amples from the most common and familiar facts to illustrate principles, and 
on the other hand have endeavored to explain similar facts by a recurrence 
to principles previously established. 

* For a knowledge of these the student is referred to the author's Dic- 
tionary of Chemistry, Farraday's " Chemical Manipulations," Gray's " Ope- 
rative Chemist," Silliman's Elements, Hare's Compendium, Thenard's 
Traite de Chemie, &c. 

74 J. Concluding remarks. 



PART III. 

ORGANIC CHEMISTRY. 



CHAPTER XXXI. 

CONSIDERATIONS ON THE SUBJECT OF ORGANIC CHEMISTRY. VEGE- 
TABLE CHEMISTRY. PROXIMATE PRINCIPLES AND ULTIMATE ELE- 
MENTS. VEGETABLE ACIDS. 

742. Organic Chemistry treats of animal and vegetable substances, 
the elements which enter into their composition, and their modes 
of combination and arrangement. Though organic substances 
differ greatly from inorganic, they present us with no new ele- 
ments,but the vital power produces, in plants and animals, changes 
unlike any of the effects of mere mechanical action. Inorganic 
substances generally possess some peculiar principle, which 
distinguishes one from another ; as in the acids, where one 
contains nitrogen, another sulphur, another phosphorus, &c. 
But organic products, with few exceptions are composed of the 
same elementary principles, varying only in their proportions. 
These principles are mostly carbon, oxygen, and hydrogen \ 
nitrogen is less abundant in plants than in animals. Lime,po-. 
tassa, iron, phosphorus, and some other substances usually 
exist in organic matter, though but in small proportions. 

743. It is beyond the power of science to explain in what 
manner the living principle operates in plants and animals, pro- 
ducing in the former, secretions of sap, gum, resin, oil, &c, and 
in the latter, secretions of a very different nature, as blood, bile, 
&c. Neither is the chemist able, in organic chemistry, to prove 
the results of his analysis by synthesis. Although analysis 

742. What is Organic Chemistry ? Cause of the difference between or- 
ganic and inorganic substances. 

743. Effects of the living principle. Organic compounds cannot be re- 
composed. Transmutation of matter exhibited in organic substances. 



ORGANIC CHEMISTRY. 285 

enables him to ascertain the simple elements which exist in 
gum or sugar, he cannot, by the union of hydrogen, oxygen, and 
carbon, in the same proportions in which they constitute these 
apparently simple compounds, form similar ones ; but water and 
carbonic acid x only, result from his combination. If the simplest 
products of vegetable organization cannot be imitated by man, 
much less can he produce any action which bears the remotest 
analogy to that of the mysterious principle of life. Every plant and 
animal may be considered as a laboratory, in which a presiding ge- 
nius is carrying on a process of transmutation wholly unintelligible 
to those who behold the result. Out of the dust of the earth 
springs a beautiful plant, which drinking in the most offensive 
vapors, exhales the sweetest fragrance, and glowing with bright, 
or delicate tints, forms a strong contrast with the dark unsight- 
ly soil which gave it birth. The same elements moreover goto 
form the calyx, petals and pollen of the flower, with its stem, 
leaves and roots. Where is the chemist who can explain the 
cause of the various colors, texture and odor of these different 
organs, all resulting from the same elements, placed in the same 
circumstances of air, moisture, light and heat 1 

In the young infant, how rapidly does milk become changed 
into fleshy fibres, and cellular membranes, giving roundness and 
beauty of outline to the limbs, while at the same time it is 
adding hardness to the incipient bones, and firmness to the un- 
strung muscles ! 

744. Animal and vegetable substances are all decomposed by 
a red heat, and most of them at a temperature much below this. 
When heated in the open air, or with substances which yield 
oxygen freely, as the oxide of copper, for example, they burn, 
and are converted into water and carbonic acid ; but if exposed 
to heat in vessels from which atmospheric air is excluded, very 
complicated products ensue. A compound consisting only of 
carbon, hydrogen, and oxygen, yields water, carbonic acid, car- 
bonic oxide, carburetted hydrogen of various kinds, and proba- 
bly pure hydrogen. Besides these products, some acetic acid 
is commonly generated, together with a volatile oil which has a 
dark color and burnt odor, and is hence called empyreumatic oil. 
A substance containing nitrogen only in addition to carbon, ox- 
ygen and hydrogen, yields ammonia, cyanogen, and probably 
free nitrogen. 

745. Organic products are distinguished by the following 
characteristics : 

744. Decomposition of animal and vegetable substances. 

745. Characteristics of organic products. 



286 ORGANIC CHEMISTRY. 

1. They are composed of the same elements. 

2. They readily undergo spontaneous decomposition. 

3. They cannot be formed by a direct union of these prin- 
ciples. 

4. They are all decomposed at a red heat.* 

746. Every distinct compound which exists ready formed in 
organic bodies is called a proximate or immediate principle, in 
distinction from the ultimate elements, which remain when these 
principles are reduced to their simplest parts. Thus gum and 
turpentine are among the proximate principles of plants, gelatin 
and albumen among those of animals. Carbon, oxygen, &c. 
are the ultimate elements. 

VEGETABLE CHEMISTRY. 

747. The proximate principles of plants are either confined 
to a particular part, or distributed over the whole, thus poll enin 
is found only in the pollen of flowers, while sugar exists in the 
juices diffused throughout, the whole body of many plants. 
There are various methods of procuring these proximate prin- 
ciples. The sap of the sugar maple, cane and beet yield sugar on 
being concentrated and evaporated by boiling. Starch is made 
by mechanical division of the potatoe, corn, and some other 
leguminous plants, and then washing the particles in which it 
exists, in pure water. On letting the water stand, the starch 
subsides. Volatile Oils are obtained by distillation. More than 
forty vegetable proximate principles have been discovered. 

748. There are still many difficulties in the way of an accurate analysis 
of vegetable principles, though this subject has within a few years received 
much attention. The observations of Gay Lussac and Thenard, led them 
to form the following general conclusions with respect to the constitution of 
vegetable substances. 1. A vegetable substance is always acid, when the 
oxygen, in relation to hydrogen is in greater proportion than to form water, 
or in other words when oxygen is in excess. 

2. When hydrogen is in excess, or when the oxygen is in relation to it, 
in a less proportion than is necessary to form water, the body is resinous, 
oily, or alcoholic. 

3. When the oxygen and hydrogen are in the proportions to form water, 
or neither in excess, the body is neither acid, resinous, oily, &c, but sac- 
charine, as sugar ; mucilaginous, as gum, &c. 

• Turner. 

746. Distinction between proximate principles and ultimate elements. 

747. Situation of the proximate principles of plants. Number of vegeta- 
ble proximate principles. 

748. Conclusions of Gay Lussac and Thenard respecting the constitution 
of vegetable substances. 



VEGETABLE ACIDS. 287 

749. In conformity with these views of the French chemists, a classifica- 
tion of proximate principles has been made by Turner. " These laws," he 
remarks, " are not rigidly exact, nor do they include the vegetable products 
containing nitrogen, but for want of a better principle of classification I 
shall follow M. Thenard in making them to a certain extent the basis of my 
arrangement." 

Division of proximate principles. 

1. Vegetable acids. 

2. Vegetable alkalies. 

3. Oils, resins, alcohol ; substances with an excess of hy- 
drogen. 

4. Sugar, starch, gum, &c, when hydrogen and oxygen are 
in proportions to form water. 

5. Compounds which are not known to belong to the other 
divisions, as coloring matter, tannin, &c. 

VEGETABLE ACIDS. 

750. The vegetable acids are composed of oxygen, hydrogen 
and carbon ; they redden blue vegetable colors, have mostly a 
sharp taste, and neutralize salifiable bases, forming salts. 

The names of these acids are generally derived from the vegetables in 
which they exist in the greatest quantity. They are decomposed by heat, 
or by hot nitric acid. The products of their decomposition are carbonic 
acid and water. 

751. Acetic Acid. Of all the vegetable acids this is the most 
extensively used. It exists ready formed in the fruit of the 
Phus typhinus (sumach,) Sambucus nigra (elder,) and the sap of 
many plants, either free or combined with lime, or potassa. It 
is one of the principal products of the acid fermentation. It gives 
to vinegar its sourness. Besides acetic acid, vinegar contains 
more or less water, mucilaginous matter, alcohol, and various 
salts in solution. 

In France, vinegar is made by exposing wine to the acid fermentation, 
in England, malt liquors are used for this purpose, and in the United 
States, most of the vinegar is made from cider. As oxygen is here the acidi- 
fying principle, the cider should be placed where the sun and air may 
have access, and be furnished with some of the mother of vinegar, a mucila- 
ginous, whitish, ropy substance which is usually found at the bottom of strong 
vinegar. This substance seems equally necessary in hastening the acetous 
fermentation of cider, as yeast is in promoting the vinous fermentation of 
bread. The vinegar from wine contains a certain portion of the bitartrate 
of potassa which may be obtained by evaporation. Vinegar as obtained 

749. Turner's classification of proximate principles. 

750. General characteristics of vegetable acids. Number. Derivation 
of the name of these acids. Decomposition, &c. 

751. Acetic acid. Vinegar. Making vinegar. Wine vinegar. Distilla- 
tion. Freezing, &c. 



288 OXALIC ACID. 

pure by distillation, forms acetic acid. When vinegar is exposed to severe 
cold, some of its water freezes, and it becomes stronger, or more like pure 
acetic acid. 

752. Acetic acid is also obtained by purifying the pyroligneous 
or empyreumaticacid, which is procured from the carbonization 
of wood in close vessels. On being distilled, a brown transpa- 
rent liquid is obtained, having a strong smell of smoke. This 
pyroligneous acid is beneficial in the preservation of meat, to 
which it imparts a flavor like that obtained in the common pro- 
cess of smoking. 

Pure acetic acid is obtained from the binacetate of copper, (crystalized 
verdigris,) and from the acetates of potassa and soda. The acetate is dis- 
tilled with sulphuric acid, which, uniting with the base, disengages acetic 
acid. 

753. Properties. Acetic acid is very volatile, has a sour 
taste, and other acid properties ; its odor is refreshing, and 
hence vinegar is often burnt in sick rooms. Its crystals con- 
tain one equivalent of acid with one of water. The strongest 
acid is a hydrate ; it cannot be obtained without a portion of 
water. According to the late analysis of Leibig, acetic acid 
is composed of the following elements, Car. 4, Hyd. 4. Ox. 4.* 

754. Acetic acid acts readily on ammonia and most of the 
metallic oxides, forming salts called acetates. 

Acetate of ammonia is used in medicine under the name of spirit of min- 
derus ; it is obtained by saturating carbonate of ammonia with acetic acid. 
The acetates of soda and potassa, are employed for obtaining acetic acid. 
They may be prepared by neutralizing potassa and soda with distilled vine- 
gar. The acetate of potassa exists in the sap of many plants. The acetate 
of alumina is used by dyers and calico printers ; that of baryta as a re-agent 
in Chemistry. 

Acetate of Copper furnishes the green paint known as verdigris ; 
this may be obtained by exposing metallic copper to the vapor 
of vinegar ; the metal first oxidizes by the action upon it of 
the oxygen of the air, and the oxide then unites with the acid. 
There are several definite compounds of copper and acetic acid. 
Acetate of lead is made by distilling the carbonate of lead, or 
litharge in distilled vinegar. It has a sweetish taste, and is 
known as sugar of lead. It is much used in medicine, and in 
the arts. 



OXALIC ACID. " 

755. So named from the Oxalis acetosella t or wood-sorrel, 

* The numbers denote equivalents. 

752. Pyroligneous acid. Acetic acid obtained by the distillation of ace~ 
tates. 

753. Properties of acetic acid. Its constituent elements. 

754. Acetates. Acetate of copper. Acetate of lead. 



TARTARIC ACID. 289 

where it was first discovered by Scheele combined with potassa, 
forming the salt called oxalate of potassa. 

Oxalic acid may be obtained by heating nitric acid in a retort with sugar, 
starch, alcohol or most vegetable acids. It is much used to remove colors 
occasioned by the oxides or salts of iron. The strong sour taste of this 
acid is apparent in the different species of sorrel; the bruised green leaves 
of these plants, on account of the presence of this acid, are efficacious in 
removing stains, and iron rust from linen. In combination with lime, oxalic 
acid exists in the leaves of the garden rhubarb. It acts as a poison on the 
animal system. 

Its crystals contain 4 equivalents of water (9x4=36) with one equivalent 
of acid 36, their equivalent number is therefore 72. " It is singular, 5 ' says 
Silliman, " that this powerful acid in firm crystals should be midway between 
the two gases carbonic acid and carbonic oxide, and it may even be regarded 
as composed of 1 equivalent of carbonic acid, 22, and one of carbonic oxide, 
14=36. It has the composition of a mineral acid, and it has been proposed 
to call it the carbonous acid which its composition would fully justify." 

The combination of oxalic acid with salifiable bases forms 
salts called oxalates, and sold under the name of salts of sorrel 
and salts of lemon ; the latter name however belongs to the 
nitrates, which we have yet to notice. The binoxalate of po- 
tassa, called salt of sorrel is used to remove stains of iron and 
ink. One equivalent of the acid gives to the iron forming a 
soluble oxalate of iron, and leaving a soluble oxalate of potassa. 
The quadroxalate of potassa is obtained by digesting the bin- 
oxalate with nitric acid, which, uniting with half the base, 
leaves the other half combined with the whole of the oxalic acid, 
of which there are now four proportions with one of potassa. If, 
of 4 parts of this salt, 3 are decomposed, the disengaged potassa 
can be exactly saturated with the acid which may be obtained 
by the decomposition of the 1 remaining part. 

The nature of the oxalates of potassa beautifully illustrates 
the law of multiple proportions. Their composition is as 
follows. 

Equiv. Equiv. Base. Acid. Equiv. 
oi base, of acid. 
Oxalate contains 1 -f— 1 
Binoxalates " 1 -f 2 
Quadroxalates " 1 -j- 4 

TARTARIC ACID. 

756. Was first obtained from cream of tartar, (bitartrate ofpo 
tassa,) from whence it received its name. It exists in the tama- 

755. Name, discovery, &c. of oxalic acid. Method of obtaining it. Uses, 
&c. Composition of its crystals. Oxalates. Binoxalate of potassa. Qua- 
droxalate of potassa. Composition of the oxalates of potassa. 

756. Tartaric acid, derivation of its name, plants in which it exists, &c. 
Mode of obtaining it. Properties. Pyrotartaric acid. Double salts. 

25 



48 


+ 


36 


= 84. 


48 


+ 


72 


= 120. 


48 


+ 


144 


= 192. 



290 MALIC ACID. 

rind, pine apple and many other acidulous fruits, also in balm, 
sage, and probably sumach. 

It is obtained by decomposing the bitartrate of potassa by carbonate oi 
lime. Carbonic acid goes off with effervescence, and one equivalent of the 
insoluble tartrate of lime is precipitated, while one equivalent of the neutral 
tartrate remains in solution. The precipitate is washed and then mixed 
with water containing some sulphuric acid ; the latter by uniting with the 
base of the tartrate, disengages tartaric acid, which when filtered and eva- 
porated is obtained in prismatic crystals. 

Tartaric acid possesses strong acid properties. It is used in 
fevers as a cooling drink. With soda, it forms an effervescing 
mixture, the tartrate of soda. 

This acid is remarkable for its tendency to form double salts among which 
are the tartrate of antimony and potassa, or the tartar emetic of medicine ; and 
the tartrate of potassa and soda, or Rochelle salt. Pyrotariaric acid is the re- 
sult of destructive distillation of tartaric acid. 

757. Bitartrate of potassa, cream of tartar exists in the juice 
of the grape, and is found lining the sides and bottom of wine 
casks. Owing to the insolubility of this salt in alcohol, it is 
gradually deposited during the vinous fermentation, especially 
of the red wines. In a crude state, it is called wine stone. 
This crude tartar is purified by dissolving, filtering, and crystali- 
zing. White crystals are skimmed ofTthe surface of the solution, 
these are called cream of tartar. Its peculiar sour taste is well 
known, and it has other acid properties. It is valuable in me- 
dicine, and is composed of 2 equiv. of acid and 1 of base. 

758. Tartrate of potassa or soluble tartar, was formerly used 
in medicine, under the name of vegetable salt. 

759. Citric acid is named from the genus of plants, Citrus 
containing the orange and lemon. 

It may be obtained by pouring lemon juice upon chalk, and decomposing 
the citrate of lime thus formed, by sulphuric acid. The sulphate of lime be- 
ing insoluble, is separated from the liquid citric acid by filtering. Large 
transparent crystals are obtained by evaporating the liquid. 

. It is used as a substitute for lemon juice, and for effervescing draughts 
with the carbonates of soda; the effervescence is caused by the escape of 
carbonic acid gas, and the liquid is then a solution of citrate of soda. Spots 
caused by iron and ink are removed by citric acid. Its crystals are remar- 
kable for not being affected by the air. When heated, they suffer the 
watery fusion, the acid decomposes and a peculiar compound called hydro- 
citric acid sublimes. Scheele first ascertained that the sourness of the lemon 
and lime were owing to the presence of the peculiar acid, now called the 
citric. This is often combined with malic acid in red fruits. The only 
citrate known to exist in nature is that of lime, which is found in very small 
quantities in fruits containing citric acid. 

760. Malic acid is contained in the apple, Pyrus mains. It 

757. Bitartrate of potassa. 

758. Tartrate of potassa. 

759. Citric acid, how obtained. Uses. Crystals, &c. Citrate of lime. 

760. Malic acid. Malates. Cause of the specific flavor of fruits. 



GALLIC ACID. 291 

exists in the juices of the cherry, strawberry &c. It may also 
be obtained by digesting sugar with three times its weight of 
nitric acid. 

Its salts are called malates. When sheet lead is steeped in 
apple juice, malate of lead is formed. The malates are usually 
distinguished from the citrates in being more soluble. Malic, 
citric and tartaric acids, together with sugar, mucilage and 
some other principles, give their flavor to fruits, and according 
as one or the other acids, or sugar prevails, is their specific 
flavor. In the lemon, citric acid is greatly in excess ; in the 
orange, it is generally neutralized by sugar. In sour apples, 
malic acid is in excess ; in the whortleberry and strawberry 
malic and citric acids exist in nearly equal quantities, with a 
large proportion of sugar. In the grape the tartaric acid is in 
excess. As fruits ripen, they usually contain a larger propor- 
tion of sugar. 

761. Benzoic acid is obtained from benzoin, the gum of the 
Styrax benzoe, a plant of the East Indies. It is also found in 
castor, cinnamon, in some volatile oils, in the flowers of the 
Trifolium melilotus, and other vegetables as well as some 
animal substances. Its taste is rather sweetish, but it is deci- 
dedly acid in its effect on vegetable colors, and with alkalies. 
Its crystals are white with a silky lustre. It gives to the 
paregoric elixir its taste and peculiar aromatic odor. It burns 
with a yellow flame. Its salts are called benzoates. 

762. Gallic acid was first discovered by Scheele, in 1786, in 
gall-nuts, or the excrescences found upon the leaves of a species 
of oak, supposed to be occasioned by the puncture of an insect 
whose egg is often found in the center of the nut. The nuts 
are about the size of a pigeon's egg, of a brown color and un- 
even surface. They are known in commerce as nut-galls, and 
are used in domestic coloring to produce slate color and black. 
Gallic acid, at first supposed to be peculiar to the gall nut, is 
now known to be associated with tannin in the barks of most 
trees, and in astringent vegetables. 

It is an important test with the metals. It precipitates iron 
deep black, and with tannin forms the basis of ink and black 
dyes. Ink is a mixture of the gallate and tannate of iron, and 
is soluble in the acid which is always present in this fluid ; 
thus, when ink becomes thick, we dissolve it by adding weak 

761. Plants which contain benzoic acid. Properties. Salts. Benzoates. 

762. Discovery of Gallic acid. Gall nuts. Substances containing gallic 
acid. Scheele's method of obtaining this acid. Crystals and properties of 
gallic acid. Ink. Cause of the stains made by tea on knives, &c. Dis- 
tinction between gallic acid and tannin. Gallates. 



292 CARBAZOTIC ACID. 

vinegar. The black stains caused by tea, on knives and other 
iron or steel utensils, are owing to the action of gallic acid and 
tannin, upon iron. Gallic acid is distinguished from tannin by 
giving no precipitate in a solution of gelatine. The salts of 
this acid are called gallates. The pergallate of iron is blue, the 
gallates of potassa and soda are colorless. 

763. Ellagic {ellagique) acid was so named by the French Chemist Bea- 
connot, by an invasion of the word galle (gall.) Thenard supposes that it 
forms salts with the alkalies, which he terms ellagates; he considers that 
there is a nentral ellagate of potassa, which is soluble and greens vegetable 
blues ; and an acid ellagate which is white and insoluble. He suggests that 
the ellagic acid does not exist in the gall-nut, but is formed during the pre- 
paration of gallic acid when tannin decomposes by contact with the air. 

764. We have now described the most important of the vegetable acids, 
many of which are indispensable in manufactures and the arts. There 
are others which are less known ; as, Mucic or eaccholactic acid (so 
called from mucus, gum) which was obtained by Scheele, by the action 
of nitric acid on gum, sugar or milk,* &c. The precipitate is in the form 
of a white, gritty powder, with feeble acid properties. When decomposed 
by heat, it yields, besides the usual vegetable products, a white sublimate 
called pyromucic acid. The saccholactates have been little studied. This 
acid belongs both to animal and vegetable compounds. 

765. Pectic acid derives its name from the Greek pedis, coagulum, being 
remarkable for its tendency to coagulate or to exist in a gelatinous form. 
It was first obtained by Beaconnot from the pulp of carrots, boiled with po- 
tassa ; the alkali unites with the pectic acid and forms a gelatinous mass 
which is the peclate of potassa. On adding an acid, the pectate decomposes, 
giving up its base to the new acid, and disengaging pectic acid in the form 
of jelly, which is insoluble in cold water. 

766. Indigotic and carbazotic acids are obtained by the action of nitric 
acid on indigo. When indigo is boiled in diluted nitric acid, carbonic, 
prussic and nitrous acids are evolved, and in the liquid, besides carbazotic 
acid, resinous matter, &c, a peculiar acid is found called by Chevreul the 
acid of indigo. 

The carbazotic acid appears in yellow crystaline scales. It acts like a 
strong acid upon metallic oxides, forming salts called carbazotales. The 
indigotic acid changes to carbazotic by the action of strong nitric acid, dis- 
engaging carbonic acid and nitrous acid fumes, and producing a small por- 
tion of oxalic acid. The change appears to depend on the loss of both car- 
bon and oxysen ; the composition of the two acids appear to be as follows : 
Indigotic acid, Car. 15 equiv. ox. 10, nit. 2. Carbazotic acid, Car. 10, 
equiv. ox. 10, nit. 2. 

The name carbazotic is derived from carbon and azote, the latter being 
the name by which French chemists usually designate nitrogen. 

* The word saccholactic is derived from saccharum sugar, and lacte milk. 

763. Origin of the name ellagic acid. Ellagates. Thenard's opinion of 
the production of ellagic acid. 

764. Mucic or Saccholactic acid. 

765. Pectic acid. 

766. Mode of obtaining indigotic and carbazotic acids. Properties of 
these acids. Change of the indigotic to the carbazotic acid. Composition 
of the two acids. Derivation of the name carbazotic. 



VEGETABLE ALKALIES. 293 

767. Succinic acid is named from succinum, amber, from which it is obtain- 
ed. It was formerly called salt of amber. When powdered amber is heated 
in a retort, the acid sublimes, and is condensed in the receiver. It crys- 
talizes into anhydrous prisms. Its salts are called succinates. 

Camphoric acid is the product of the action of 14 parts nitric acid, with 1 
of camphor, at the temperature of 77° F. Its salts are called camphorates. 

768. Moric or moroxylic acid is found combined with lime in the morus 
alba or white mulberry. Kinic acid exists in combination with lime in the 
cinchona. (Peruvian bark) Meconic acid is combined with morphine in 
opium. Zutnic acid, from zurne, yeast, was discovered by Beaconnot in 
vegetable substances which have passed through the acetous fermentation ; 
from more recent observation it appears not to be essentially different from 
acetic acid. 

Hydrocyanic or prussic acid, exists in many plants, as bitter almond, peach 
leaves and blossoms, &c. 

Rheumic acid was formerly supposed to exist as a distinct acid in the gar- 
den rhubarb. (Rheum). It is now considered as indentical with the oxalic 
acid. Bcletic acid is a peculiar substance discovered by Beaconnot in mush- 
rooms, called familiarly touch wood, — in Botany Boletus igniarius. Suberic 
acid is procured from the cork plant. (Quercus sube? .) 

We might extend our list of vegetable acids ; but it is highly probable 
that future discoveries may greatly reduce their number, by showing many 
of those which are now considered different to be the same, modified by pe- 
culiar circumstances ; on the other hand, it is very possible that acids may 
be discovered whose existence is now unknown. 



CHAPTER XXXII. 

VEGETABLE ALKALIES, OILS, RESINS, &C. 

769. By the name vegetable salifiable bases, or alkalies, is de- 
signated the proximate principles of certain vegetable substances, 
which united with acids, saturate them in a greater or less 
degree, and form with them combinations, which may, properly, 
be called salts. 

The discovery of these vegetable bases was made by M. Ser- 
tuerner, in 1805, in some experiments upon opium. But his 
publication of the discovery, attracted little attention, until 
some new communications of the author awakened chemists to 
the nature and importance of the subject. Such researches have 
now been made,as prove that the property possessed by many ve- 
getable substances,of acting powerfully on the animal economy, 

767. Succinic acid. Camphoric acid. 

768. Moric acid. Kinic acid. Meconic acid. Zumic acid. Hydrocyanic 
or prussic acid. Rheumic acid. Boletic acid. Number and distinctive 
characters of vegetable acids noi entirely settled. 

769. Description of vegetable alkalies. Their discovery by Sertuerner. 
Chemists awakened to the importance of the discovery. 

25* 



294> MORPHIA. 

is owing to the presence of peculiar active principles, and that 
to obtain those, separate from a mass of useless, or mere 
counteracting matter, is a great desideratum in medicine. 

770. For example ; the Peruvian bark, cinchona, had long been in high 
repute for its medicinal powers ; but it was evident that, combined with 
the energetic principle of the bark, were others, such, for instance, as tan- 
nin and woody fibre, which could not aid in producing the desired specific 
effect, that to crowd the weak stomach with useless or hurtful substances 
in order to introduce a medicinal one, was contrary to the dictates of com- 
mon sense as well as the principles of science. With this important and 
definite object in view, two French chemists, Pelletier and Caventou, com- 
menced a series of experiments with cinchona, which resulted in the dis- 
covery of its active medicinal principle. This they called quinine. A small 
quantity of this concentrated alkali produces powerful effects on the human 
system, particularly in intermitting fevers, and other diseases. 

771. The vegetable alkalies are not found free in nature, but 
exist in plants, combined with acids forming natural salts, more 
or less soluble in water. In order to obtain the alkaline princi- 
ple, the vegetable substance is digested in water, and the salt 
being thus dissolved, some powerful salifiable base, as ammonia 
or potassa is added. This uniting with the acid, leaves the al- 
kali free ; the latter being insoluble in water may be obtained 
by precipitation. 

Properties. Vegetable alkalies are soluble in hot alcohol, and 
crystalize on cooling. They are solid, bitter or acid, inodorous, 
change blue vegetable colors green, and are heavier than water. 
When decomposed by fire, they yield ammonia; this is formed 
by the carbon and nftrogen,* which, with hydrogen and oxygen, 
constitute their ultimate elements. They form combinations 
with sulphur, and are soluble in chlorine and iodine. When 
salts with vegetable bases are decomposed by the voltaic pile, 
the alkali appears at the negative, and the acid at the positive 
pole. 

772. Morphia or morphine, so called from Morpheus, (known in heathen 
mythology as the God of sleep) is the narcotic principle of opium, in which 
it exists combined with meconic acid. Opium is the dried juice of the 
poppy, and besides meconic acid, contains various principles, as narcotine, 
gum, resin, lignia, oil, and caoutchouc or gum elastic. Morphia in most 
cases, acts on the animal system as a violent poison ; but did it meet with 
no acids in the stomach, it would be inert on account of its insoluble nature ; 

* Nitrogen was formerly considered as a distinctive character of animal 
matter ; it is now known to exist in many vegetable compounds, though 
more sparingly than in animal. 

770. Combination of the medicinal principle of the Peruvian bark, with 
useless or hurtful matter. Discovery of quinine. 

771. Method of obtaining the alkaline principle of plants. Properties of 
vegetable alkalies. 

772. Morphia, with what acid combined. Various principles of opium. 
Antidotes to the poison of morphia. Uses. Acetate. 



♦ STRYCHNIA. 295 

thus experiments have given different results, as the stomach of the animals 
into which it has been introduced have contained more or less acid. 

When morphia has been taken in too large quantity, a solution of ammo- 
nia may decompose the soluble salt, formed by it with the acetic and other 
acids in the stomach, and the vegetable alkali will thus be precipitated in 
an insoluble state. Ammonia and other alkalies are recommended in 
cases where laudanum or any preparation of opium is taken in excess; they 
decompose the meconate of morphia, which is the active principle and pro- 
duce an insoluble precipitate of morphia. Infusions of coffee and nut-galls 
counteract the effects of morphia, by forming with it insoluble compounds. 

When properly used, morphia is a highly valuable medicine ; it is said to 
** produce the soothing effects of opium, without causing the feverish excite- 
ment, heat, and headache which so often accompany the use of that drug." 
The acetate of morphia is very soluble, and the most active of the salts of 
this alkali. The constituent elements of morphia are, Car. 34, Hyd. 18, 
Nit. 1, Ox. 6,=284. 

773. Meconic acid, so called from the Greek mekon, poppy, is sour and 
bitter; it reddens vegetable colors and gives a red tint to the persalts of 
iron and an emerald green to sulphate of copper. It seems inactive with 
respect to the animal system. The meconate of morphia, therefore, must 
owe its energetic action to the increased solubility of morphine in the state 
of a salt. 

774. Narcotine is an independent principle which, though not alkaline we 
shall here notice on account of its association with meconic acid and mor- 
phia. The powerful effects of opium have been attributed to narcotine. 
Acids mitigate its power ; and this appears to explain the use of vinegar in 
counteracting some of the effects of opium, and also the comparative mild- 
ness of the black drop, in which the narcotine is in solution in vinegar, nitric 
or tartaric acid." 

775. The medicinal property of the Peruvian bark is found to reside in 
two alkalies, the cinchonia and the quinia or quinine ; the former exists in 
the pale bark, quinia in the yellow bark ; while both are contained in the 
red bark. These two vegetable alkalies are found to bear to each other 
much the same relation as potassa and soda relatively sustain ; they exist 
in combination with kinic acid. Quinine is mostly used in the form of a 
sulphate. According to the latest analyses, these two alkalies are constitu- 
ted as follows, Cinchonia, Car. 20, Hyd. 13, Nit. Ox. 1±=158. Qu'inia, 
Car. 20, Hyd. 1, Nit. Ox. 2=162.* 

776. Strychnia is an intensely bitter alkali obtained from the Strychnos 
nux-vomica, and exists in the Upas tree of Java; it is a deadly poison. 

Brucia was discovered in the Brucia antidysenterica ; it has since been 
found in the plants which yield Strychnia, and resembles that alkali in its 
poisonous properties, but is less active. 

Sanguinaria has been discovered in the sanguinaria canadensis or blood 
root. The medicinal virtues of the blood root are said to exist in this alka- 
line principle. 

* For explanations of chemical signs see the Author's Dictionary of 

Chemistry. 

773. Meconic acid. 

774. Narcotine. 

775. Medicinal properties of the Peruvian bark, &c. Constituent ele- 
ments of cinchonia and quinine. 

776. Strychnia. Brucia. Sanguinaria. Veratria. Emetia. Codeia. 
Cania. Parilla. 



296 FIXED OILS. 

Veratria is the medicinal principle in the white hellebore, Veratnim album, 
and the Colchicum autumnale or meadow saffron, plants which have a pecu- 
liar acid nature caused by the union of the alkaline principle with gallic 
acid. 

Emetia is the alkaline principle which gives ipecacuanha its emetic pro- 
perties. 

Codeia was discovered in 1832 by Robiquet in the hydrochlorate of mor- 
phia. Conia is the active principle of the Coniummaculatum. Parilla is 
found in sarsaparilla. 

777. Almost every plant distinguished for energetic action will probably 
be found to owe its powers to some peculiar alkaline principle. Thus in 
the Atropia belladona or deadly night shade, has been discovered atropia, 
which, with acids forms salts of a peculiar kind, giving off from their watery 
solutions vapors which produce giddiness, violent headache, and dilatation 
of the pupil of the eye. From the black henbane, Hyoscyamus niger, is ob- 
tained an alkali called Hyosciamia. From the Digitalis or fox glove, is ob- 
tained digitalia which seems to possess the concentrated medicinal virtues 
of the plant; and from the Datura Stramonium, is obtained the alkali datu- 
ria. These vegetable alkalies were at first distinguished by the termina- 
tion ine, as quinine, morphine, emetine, &,c. But the termination in a, is gen- 
erally adopted, as being in conformity with the names of other alkaline 
substances, potassa, soda, magnesia, &c. 

Vegetable substances which contain Hydrogen in excess. 

778. Substances which contain an excess of hydrogen are 
generally oily, resinous, alcoholic or etherial ; being also abun- 
dant in carbon, they are very fusible and combustible. When 
heated in a retort many of them volatilize without any change 
in their constitution, others decompose, producing large por- 
tions of oil and a carbonous residuum. When exposed to a high 
temperature in a porcelain tube, they all suffer ultimate decom- 
position, produce carburetted hydrogen gas, carbon, and oxide 
of carbon. Most of these substances are insoluble, or nearly so, 
in water, but very soluble in alcohol. 

OILS. 

779. Oils are of two kinds, fixed or fat oils, which are not 
volatile, and give a permanently greasy stain to paper : and 
volatile or essential oils, which, when dropped on paper, may be 
dissipated or volatilized by a gentle heat. 

Fixed Oils. 

780. Fixed Oils are chiefly obtained from the seeds of plants, 

777. Peculiar alkaline principles of plants. Atropia. Hyosciamia. Digita- 
lia. Daturia. 

778. Nature of vegetable substances which contain hydrogen in excess. 
Effects of heat upon these substances. 

779. Two kinds of oils. 



FIXED OILS. 29* 

and mostly from the tficotyledonous kinds ; as the almond and 
various kinds of nuts, linseed, &c. The oil of olives or common 
sweet oil, is extracted from the pulp which surrounds the olive 
nut. These oils are usually procured by subjecting to great 
pressure the crushed seed or pulp, gently heated, it may also be 
procured by the action of boiling water upon the pulverized oily 
seeds. 

Properties. The fixed oils, with few exceptions, are fluid at the common 
temperature. They usually swim on water, but sink in alcohol. They com- 
bine with alkalies or metallic oxides, forming soaps which are soluble or 
insoluble according to the nature of the oxide. When exposed to the ac- 
tion of the atmosphere they absorb oxygen, become thick and rancid, and 
redden vegetable blues. Such as dry so hard as not to stain paper are call- 
ed siccative or drying oils ; linseed oil is of this kind, and hence its use in 
painting. Drying oils, mixed with lamp black, form printer's ink. During 
the drying process large portions of oxygen are absorbed. This absorption - 
is sometimes so rapid, and causes the disengagement of so much free calo- 
ric, that light, porous, combustible matters, such as lamp black, hemp, cot- 
ton and the like may be kindled by it. "Substances of this kind moistened 
with linseed oil, have been known to take fire or produce spontaneous com- 
bustion within 24 hours, a circumstance which has been repeatedly the 
cause of extensive fires in ware houses and cotton manufactories." (Tur- 
ner.) 

Though fixed oils do not unite with water, they may be suspended in it 
by the aid of sugar or mucilage, foiming an emulsion. Sulphur and phos- 
phorus aided by heat, dissolve in the fixed oils ; and the solution with sul- 
phur may be crystalized on cooling. Iodine and chlorine absorb a portion 
of the hydrogen of the fixed oils, and form hydriodic and hydrochloric acids. 
Potassium and sodium have little action upon these oils ; though in time 
they absorb a small portion of their oxygen, and when oxidated thus form 
with them a soapy compound. Sulphuric acid thickens the fixed oils ; strong 
nitrie acid acts so forcibly upon them as sometimes to produce combustion. 
Oxide of lead or litharge, heated with oil produces a drying liquid used as 
oil varnish ; olive oil, with the same oxide, forms the diachylon plaster. Oils 
aid in the oxidation of metals ; oiled copper soon becomes green, showing 
the presence of the carbonate of copper. 

Soaps of various kinds are formed by the union of oils with alkalies. 
Volatile liniment is a mixture of ammonia and olive oil. Common domestic 
soap is made of animal oil or fat combined with alkali ; but the finer kinds 
of soap are often made with vegetable oils. 

781. The principal fixed oils are linseed oil, obtained from flax-seed, and 
used with litharge for paints, varnishes and printer's ink; olive oil, from the 
fruit of the olive tree ; (the purest kind being used for the table, the infe- 
rior for soap and for lights); almond oil u=ed in medicine ; mustard seed and 
sunflower seed oils are cheap and much used by leather dressers ; oil of bean 
from the seeds of an East Indian plant is used for absorbing the volatile 
oils of aromatic plants. The perfumed oil is dissolved in alcohol, and water 
is added to the mixture ; the alcohol uniting with the water, disengages the 

780. Fixed oils, from whence obtained, &c. Properties. Drying oils. 
Effects sometimes produced by the rapid absorbtion of oxygen, by these oils. 
Emulsion. Action of sulphur, phosphorus, iodine and other substances with 
the fixed oils. Effect of oils with metals. Soaps, volatile liniment, &c. 

781. Principal fixed oils. 



298 ESSENTIAL OILS. 

volatile oil which floats on the top, and may be collected for the perfumer. 
Palm oil is used in warm countries for food, and exported for medicinal 
purposes, and to form the finer kinds of soap. Cocoa butter is not liquid at 
the common temperature, it has the flavor of chocolate. Castor oil from 
the Ricinus communis is very valuable in medicine. It does not congeal, but 
at a temperature much below zero. 

782. The volatile oils are the aromatic principles of plants 
which sometimes are confined to the flower, leaves, bark, or 
root, and sometimes diffused through the whole : but seldom 
contained in the cotyledons of seeds which furnish most of the 
essential oils. These oils may be obtained by distilling the 
plant with water. 

The operation of distilling plants is as simple as that of making fruit 
preserves, and might furnish an agreeable and feminine employment. Every 
lady may manufacture rose-water of a much better quality than that which 
is generally sold. A small distilling apparatus may be placed over a por- 
table furnace, with a quantity of water and rose petals in the boiler ; the 
aromatic principle of the rose passes over with the distilled water into the 
recipient. This product should be returned to the boiler and a new portion 
of the rose petals added, and a stronger product is next obtained. The oper- 
ation must be repeated, several times, before the water will become strongly 
impregnated with aromatic properties. The essential oil of the rose will ap- 
pear when the water is cool, in very minute quantities on the surface. But 
the proportion of oil in this flower is so small that great quantities of its 
petals are requisite for obtaining a very little oil. As the rose petals drop 
off, they may be collected and dried, or preserved by putting them into a 
large vessel and sprinkling them with salt. The salt will not come over 
with the product of distillation, nor disengage its elements. Other aroma- 
tic plants may be distilled in a similar manner. In India the oil, or attar of 
roses, is obtained by filling large casks with rose petals, covering them with 
water, and placing them in the sun, after a few days, particles of oil appear 
floating on the surface. These are collected and put into the small bottles, 
which are sold in the shops. In some cases, as in the rose, jessamine and 
lily of the valley, the Avater which passes into the recipient in distillation 
will be strongly impregnated with the aroma of the plant, while no oil may 
appear on its surface when cold. Thus, rose-water, though not visibly con- 
taining any oil, owes its aromatic property to a very small portion of essen- 
tail oil, dissolved by the water, in the distilling process. 

783. Essential oils much diluted with alcohol, are called 
essences ; twenty or thirty drops of essence do not usually con- 
tain more than two or three drops of the essential oil j in me- 
dicine, therefore, it is important to distinguish between the two, 
as over-doses of the volatile or essential oils will produce con- 
vulsions, and even death. The strong odor of flowers in a con- 
fined room is unhealthy, on account of exhalation of volatile oils. 

Properties. These oils are generally more energetic than the 
fixed oils j they are odoriferous, with a hot aromatic taste. 

782. Situation of the volatile oils in plants. How obtained ? Manufac- 
ture of rose-water. Attar of roses. 

783. Essences. Properties of volatile oils. Principal volatile oils, &c. 



RESINS. 299 

They are colorless, yellow, green or blue, very volatile and in- 
flammable ; they readily absorb oxygen from the air, and be- 
come thick. They do not easily combine with salifiable bases. 
With nitric acid they often inflame and burn brilliantly. The 
most important of the volatile oils are those of turpentine, cloves, 
nutmeg, lavender, cinnamon, peppermint, annise, and chamomile. 
784. The oil of turpentine is procured by distilling turpentine. When pu- 
rified it is called spirits of turpentine. Camphor may properly be ranked with 
the essential oils, as it is odorous, inflammable and volatile. The camphor 
of commerce is chiefly extracted from the Laurus camphora, which grows in 
Japan and the East Indies. The camphor is obtained in the form of green, 
porous masses. Crude camphor is purified by sublimation. Its odor is 
strong, but agreeable and refreshing, and its taste acid and pungent. It is 
soluble in alcohol and ether. It burns brilliantly in oxygen gas, producing 
camphoric and carbonic acids. It is lighter than water, its specific gravity 
being 0.980. It is insoluble in water. "When a few drops of a solution of 
camphor in spirits is put into a tumbler of water, the water and spirits unite 
and camphor is precipitated. Proust obtained a erystaline product from 
thyme, and some other labiate flowers, which he supposes differs little from 
camphor. Camphoric acid which results from the action of nitric acid on 
camphor, unites with salifiable bases forming salts called camphorates. Cou- 
marin is a peculiar, odoriferous, volatile principle derived from the Couma- 
rouna odorata or Tonka bean. 

RESINS, 

785. Are the thick juices of certain plants, and are often found 
combined with essential oils, which give them their peculiar 
taste and odor, and render them soft. The resins are non-con- 
ducters of electricity, but become negatively electrified, on being 
rubbed. Exposed to the action of fire, they burn with a yellow 
flame and much smoke. They are insoluble in water, but solu- 
ble in alcohol, oils, and solutions of potassa and soda. With 
the two latter they form a kind of soap. They are not decom- 
posed by air. Nitric acid rapidly decomposes them, much gas 
is disengaged, and a compound results which resembles tannin. 

786. The resin of pine has been analyzed by Gay Lussac and Thenard, 
100 parts of which were found to contain Carbon, 75.944; Hydrogen, 10. 
719; Oxygen, 13.337. 

The juice of the different kinds of pine, called turpentine, consists chiefly 
of resin combined with the volatile oil of turpentine. The resinous products 
of the different species of cone-bearing trees are distinguished by various 
names. Common turpentine is obtained by making incisions in the pine trees, 
and hardening the juice which flows out by exposure to the air and sun. 
Burgundy pitch is from the Norway spruce and larch. Tar is melted out 
from the resinous trees by a smothered fire resembling a coalpit. Lac is a 

784. Oil of turpentine. Camphor. Coumarin. 

785. Cause of the peculiar taste of the resins. Properties of resins. Com- 
position. 

786. Resinous products of the pine. Lac. Copal. Amber. 



300 wax. 

red concretion caused by the puncture of an insect upon the branches of 
the banyan, fig, and Rhamnus jugaba of the East Indies. It consists mostly 
of resin with coloring matter and wax. Shell lac contains more resin and 
less coloring matter than Stick lac. Shell-lac, in India, is cast into beads, 
and other ornaments ; it is used for red sealing wax. Stick-lac is used in 
dyeing. Copal is a brilliant, transparent resin which is chiefly used for 
varnishing. It is brought from South America and the East Indies. It is 
susceptible of becoming highly electrified by friction. Jimber resembles 
copal in appearance ; it is supposed to be of vegetable origin, though found 
in sand. It is sometimes found in beds of bituminous coal, and enveloping 
vegetable substances. It often contains insects in good preservation. It 
was in this substance that electrical phenomena were first observed ; its an- 
cient Greek name was electron. It consists of a -volatile oil, succinic acid, 
resin, and a bituminous principle. 

787. Balsams are resins containing so much essential oil as 
to render them fluid, or nearly so. They are not proximate 
principles, but rather consist of several of these principles united ; 
as resin, benzoic acid, essential oil. They are divided into 
liquid, of which the balsam of copaiba and styrax are examples, 
and solid, as benzoin and dragon's blood ; the latter is used in 
making red varnish. 
. 788. Gum resins contain gum, resin, wax, volatile oil, and ex- 
tractive matter. They are not therefore distinct proximate 
principles. The gum-resins arc valuable in medicine. Among the 
most important are myrrh, aloes, assafoetida, gamboge andguiacum. 

789. Caoutchouc, Indian rubber, or gum elastic is the concrete juice of the 
Urceola elastica, and Jatropha elastica, plants of South America. It is said 
to have been prepared from the dried juice of the milk weed, (asclepias.) 
It is white, when not blackened by smoke as is common in its preparation ; 
it is soft, flexible, very tenacious and elastic. It melts readily and burns 
with a bright flame, leaving little residuum. It is insoluble in water, alco- 
hol, alkalies and acids. The volatile oils are its proper solvents. The pu- 
rified Naphtha from coal tar dissolves it, and being a cheap article may be 
profitably employed in Indian rubber manufactories. It must contain some 
nitrogen since by destructive distillation it yields ammonia. 

Creosote exists in tar and pyroligneous acid ; it is an oily fluid, with an 
odor of smoke. 

790. Wax is extensively diffused in nature. It is found as a varnish on 
the surface of the leaves of plants, in the pollen of flowers, and in many 
trees. The wax of bees appears not to be wholly of vegetable origin, being 
composed also of some animal secretion. Huber found that bees which 
were fed solely on sugar, produced wax in as great quantities, as those 
which had access to flowers. The berries of the Myrica cerifera or bayberry, 
contain large portions of wax ; it is aromatic, of a pale green color, and is 
sometimes mixed with tallow to render candles more firm ; it has been call- 
ed bayberry tallow. Wax is usually more or less colored, and may be bleach- 
ed by exposure to the sun and air, and by the action of chlorine. Thus 

787. Balsams. 

788. Gum resins. 

789. Caoutchouc or Indian rubber. 

790. Wax. Wax of the myrica cerifera, &c. Properties of wax. Con- 
stituent principles of wax, composition, 



ALCOHOL. 301 

bees wax which is yellow and has an aromatic smell, becomes, by bleaching 
very white and destitute of odor. Wax melts at 154° F., it is insoluble in 
water, dissolves in warm ether and alcohol, but precipitates when cold. 
It is easily dissolved by the fixed and volatile oils. It has been found to 
consist of two principles, one of which called cerin is soluble, the other 
called myricin is insoluble in alcohol. The composition of bees' wax ac- 
cording to Gay Lussac and Thenard, is in 100 parts ; Car. 81.784. Nit. 
12.672 5 . Ox. 5.544. According to Liebig, Car. 20, Hyd. 20, O. 



CHAPTER XXXIII. 

ALCOHOL, ETHER, &C. 
ALCOHOL, 

791. Is a colorless, volatile liquid, of a strong odor and a 
burning taste. It is the intoxicating ingredient in all kinds of 
spirits, wine, cider and beer. It does not exist ready formed in 
plants, but is the product of vinous fermentation. Fermented 
liquids have been known from the remotest periods of history ; 
distilled liquors were first prepared by an Arabian alchemist in 
the 10th century, though they were little known, until several 
hundred years after. 

792. On account of its volatile nature, alcohol is readily obtained by dis- 
tilling fermented liquors. Pure alcohol is called rectified spirit, and when 
supposed to be entirely free from water, absolute alcohol. The purity of al- 
cohol is in an inverse proportion to its density. Common alcohol has a 
specific gravity of about 86, but when freed from water of 82. Thus the 
specific gravity of spirits is a test of their purity, which is determined by 
the hydrometer* Alcohol boils at a temperature as low as 176° F. It pro- 
duces cold during evaporation. No degree of cold has yet been known, 
with certainty, to freeze alcohol. When half water it freezes at 60° below 
zero. On account of the property of alcohol to remain liquid at the extreme 
degree of cold where mercury freezes, it is used in thermometers designed 
to measure intense cold. 

793. As alcohol burns without smoke or residuum, the spirit lamp is much 
used in laboratories. Attempts have been made to introduce alcohol into 
common use, in the place of oil, for lamps, but its use has been found dan- 
gerous, owing to its great inflammability; if accidently spilled when burn- 
ing, its whole surface will burst forth into instant flame. The products of 

• See the author's Familiar Lectures on Natural Philosophy, page 165. 

791. Physical properties of alcohol, &c. Distilled liquors first known. 

792. Mode of obtaining alcohol. Rectified spirit and absolute alcohol. 
Specific gravity. Its boiling point. Effect of its evaporation on surround- 
ing bodies. Freezing point of alcohol. How useful in thermometers ? 

793. Spirit lamp. Products of the combustion of alcohol. Its use in 
light-houses, &c. 

26 



302 ALCOHOL. 

its combustion are water and carbonic acid. The flame of alcohol directed 
upon lime or chalk produces a most vivid light, and is therefore-much used 
in light-houses. It may be inflamed by the electric spark. 

794. Alcohol dissolves most of the vegetable principles, as the essential 
oils, resins, balsams, and most of the vegetable alkalies and acids, but not 
many of the animal oils. It dissolves potassa, soda, and ammonia, but not 
the earths or metallic oxides. Phosphorus, sulphur, and iodine are spar- 
ingly soluble in Alcohol. Chlorine produces with it an oily substance, ac- 
companied with hydrochloric and carbonic acids. This oily matter seems 
to be a combination of chlorine and percarburetted hydrogen. When equal 
parts of alcohol and water are mixed, there is an elevation of temperature, 
and consequent expansion of the liquids; this mixture constitutes proof spirit. 

795. When alcohol is healed in a porcelain tube, the products of the de- 
composition are carburetted hydrogen, carbonic oxide and water. Accord- 
ing to the analysis of the younger De Saussure, the ultimate elements of al- 
cohol are 

Carbon 2 Equiv. = l2 parts in 100 52.17 

Oxygen 1 « = 8 " " 34.79 

Hvdrogen 3 « = 3 " " 13.04 



Equiv. of alcohol 23 100.00 

These elements are in the proportion to form olefiant gas and water; 
there are 2 equivalents of carbon, 1 of oxygen and 3 of hydrogen. Olefiant 
gas requires 2 eq uivalents of carbon+2 of hydrogen. Water requires 1 
equivalent of oxygen-f-1 of hydrogen. According to Liebig's formula 
the constituents of alcohol are Car. 4, Hyd. 5, Ox.-p- Hyd. Ox. =46. 

796. It was formerly asserted that alcohol did not exist ready 
formed in wine, but was generated by heat, during the distilling 
process. Mr. Brande determined this question by obtaining 
alcohol from wine without the aid of heat. He precipitated the 
acid, and extracted coloring matter by the sub-acetate of lead, 
and then absorbed the water from the alcohol by dry carbonate 
of potassa. Pure alcohol rose on the surface. The strong 
wines, Maderia, Sherry, Port, &c. contain from 18 to 25 percent 
of alcohol, and cider, ale and porter from 4 to 10 per cent. 

797. The action of the acids on alcohol produces ether. Al- 
cohol also, like water, forms with certain bodies, definite crystal- 
ine compounds, called alcoates* 

When the anhydrous chlorides of calcium, manganese and zinc, or the 
nitrates of lime and magnesia are heated with anhydrous alcohol, the com- 
pound on cooling will assume a crystaline form. A very small quantity of 
water would prevent the crystalization. The crystals are deliquescent, 
soluble both in water, and alcohol, and readily fuse in their water of crys- 
talization. 

* As crystals containing water are called hydrates. 

794. Solvent powers of alcohol. Use of Spirit. 

795. Products of the decomposition of alcohol. The elements composing 
alcohol are in the proportion to form olefiant gas and water. 

796. The question settled with respect to the existence of alcohol ready 
formed in wine. 

797. Action of acids with alcohol. Alcoates. How formed ? 



ETHER. 303 

798. Alcohol, on account of its great solvent power, and other 
peculiar properties, is an agent of great importance in medicine 
and the arts ; but however indispensible, when taken in any- 
considerable quantities into the animal system it has a poison- 
ous and fatal tendency ; and this, under whatever disguise's it 
may be presented. 

ETHER, 

799. Is an inflammable, volatile liquid, formed by the action 
of alcohol with various acids. The ethers are composed of three 
classes, the 1st containing those which are composed of oxygen, 
carbon and hydrogen ; 2d those whose acids contain hydrogen 
instead of oxygen, and 3d when the oxacid is united with alcohol. 

800. Sulphuric ether was long the only ether known. It is 
much used in medicine and the laboratory. 

It is formed by heating strong sulphuric acid with an equal weight of 
rectified alcohol in a glass retort ; ether rises in a recipient surrounded by 
ice-cold water. The operation is continued until white vapors appear in the 
retort ; after this, sulphurous acid gas, with a peculiar yellowish liquid, 
called ethereal oil, and the sweet oil of wine (sulphovinic acid,) begin to pass 
over ; longer continuance of the heat produces olefiant gas. The ether thus 
obtained is impure ; it is rectified by adding potassa, which absorbs the sul- 
phurous acid and the ethereal oil. 

801. Theory. It was long believed that sulphuric acid transformed alco- 
hol into ether, by taking from it a certain quantity of water; and the com- 
position of ether seemed to favor the theory. At present, the decomposition 
of sulphuric acid during the process for obtaining ether is admitted, and 
also that alcohol consists of 1 part of olefiant gas and 1 of water ; and ether 
of 2 of olefiant gas and 1 of water. 

802. Physical Properties. Sulphuric ether is without color, 
has a strong and fragrant odor, and a hot and sharp taste. Ac- 
cording to Gay Lussac it does not transmit the electric fluid. 
It reflects light strongly, is perfectly limpid and fluid. Its 
specific gravity when purest is about 0.70 ; It is very volatile, 
boilingat96° F. under atmospheric pressure; and at 20° below 
zero in a vacuum absorbs caloric so rapidly from surrounding 
bodies as to freeze water, and even mercury. It freezes at — 46°. 
Its vapor has a density of about 2.58, air being 100. It flows 
through a capillary tube nearly four times as fast as water, and 
eight times as fast as alcohol, but does not rise so high by 
capillary attraction as either of the other two fluids. It is 

798. Use of alcohol, and its effects on the animal system. 

799. Ether. 

800. Sulphuric ether. Preparation. 

801. Theory. 

802. Physical properties. 



304* ETHER. 

highly inflammable, burning with a blue flame ; its vapor forms 
a mixture with the oxygen gas, which explodes by an electric 
spark or on the approach of flame. 

803. " When a coil of platinum wire is heated to redness, and then sus- 
pended above the surface of ether contained in an open vessel, the wire in- 
stantly begins to glow and continues in this state until all the ether is con- 
sumed. During this slow combustion, pungent acid fumes are emitted, 
which, if received in a separate vessel, condense into a colorless liquid pos- 
sessed of acid properties. Mr. Daniell, who prepared a large quantity of 
it, was at first inclined to regard it as a sour acid which, in reference to the 
mode of obtaining it, he called lampic acid ; but he has since ascertained 
that the acidity is owing to the acetic acid, which is combined with some 
compound of carbon and hydrogen different both from ether and alcohol. 
Alcohol when similarly burned likewise yields acetic acid." — Davy. 

804. Chemical properties. Ether is somewhat less powerful 
as a solvent than alcohol, though most of the substances which 
dissolve in the latter, are dissolved in the former. It has no 
action upon the fixed alkalies, but unites with ammonia. It 
dissolves Indian rubber with great facility. When exposed to 
the light it gradually absorbs oxygen, and becomes sour, which 
is supposed to be occasioned by the formation of acetic acid. 
Ether is very inflammable, burning with a blue flame j a lump 
of sugar filled with ether thrown into a vessel of boilingr water, 
forms a burning fountain, by lighting it with a taper. Chlorine 
with ether produces spontaneous combustion and explosion. 

805. Hydrochloric ether is obtained by distilling a mixture of equal parts 
of hydrochloric acid and alcohol in a glass retort connected with Woulfe's 
apparatus. The first flask contains water, the others are empty and sur- 
rounded with ice. This ether is composed of equal volumes of hydrochloric 
acid and olefiant gas, united without condensation, as its specific gravity is 
equal to the sum of the specific gravity of the two gases; viz. hydrochloric 
acid having the specific gravity of 1.278X to alcohol having the specific 
gravity of 972=2.250, which is very near the specific gravity of hydrochlo- 
ric ether, when compared with atmospheric air. It is even more volatile 
than sulphuric ether : boils by the heat of the hand, producing by its eva- 
poration a sensation of coldness. It burns with a green flame, disengaging 
hydrochloric acid gas. From its composition it is apparent that it contains 
no oxygen gas. 

806. Hydriodic ether is obtained by distilling hydriodic acid and alcohol. 
When poured on hot charcoal it gives off the purple vapors peculiar to 
iodine. 

807. Nitric ether is made by distilling equal weights of alcohol and nitric 
acid : but the mutual action of the two substances is so violent as to render 
the process dangerous. The alcohol must be added in small quantities. 



803. Substance named by M. Daniell lampic acid. 

804. Chemical properties. 

805. Hydrochloric ether. 

806. Hydriodic ether. 

807. Nitric ether. Properties. Sweet spirit of nitre. Ultimate elements. 
Acetic ether, &c. 



SUGAR. 305 

A, (Fig. 124,) represents a Woulfe's bottle ; B, 
a receiver ; c, c, glass funnels ground to their 
necks, and glass rods ground to the funnels ; the 
acid being in one funnel and the alcohol in the 
other. 

Nitrous ether is of a yellowish color, has a 
strong odor, and burning taste. It is more vola- 
tile than sulphuric ether. With alcohol it forms 
the sweet spirit of nitre, which is valuable in 
medicine. Its ultimate elements are Car. 4, 
Hyd. 5, Ox+JVit. Ox. 3. 
Jcetic ether is formed in a manner analogous to the ether already describ- 
ed. It inflames on the approach of a burning substance, reproducing acetic 
acid. It has an agreeable odor, dissolves in alcohol, and forms a stimula- 
ting medicine. 

Oconanthic ether gives to wines their peculiar odor ; it is obtained by the 
decomposition of wine and produces intoxication when inspired. Pyroxylic 
spirit is a kind of ether formed by heating wood. 

There are other ethers formed with alcohol and the vegetable acids •, or 
the benzoic, citric, oxalic, &c. 




CHAPTER XXXIV. 

SUGAR, STARCH, GUM, &C. 
SUGAR. 

808. Under the head of sugar are included those substances 
which have a sweet taste, and when brought in contact with 
water, and a very small proportion of yeast, produce alcohol, by 
means of the vinous fermentation. This proximate principle is 
extensively diffused throughout the vegetable kingdom. Plants 
which contain it are called saccharine. Sugar is crystalizable 
either more or less perfectly, sweet, inodorous and very soluble 
in water, alcohol and other liquids. Pure sugar is hard, firm, 
and not acted upon by the air. Sugar, by friction, is phosphor- 
escent in the dark. Sulphuric acid decomposes it and disen- 
gaging charcoal, forms water, and acetic, or some other 
vegetable acid. When nitric acid is mixed with sugar, both 
substances decompose, and oxalic acid is formed. Owing to 
the quantity of carbon in sugar it is very inflammable, and 
gives off a peculiar odor in burning.* It forms but feeble 

* The carbonaceous, acetic and other vapors which exhale from burning 
sugar, possess medicinal powers ; and the practice of sprinkling sugar in 
the domestic warming pan, when used for warming the beds of those who 
are suffering under rheumatic affections or sudden colds, is founded on more 
substantial reasons than " old wives' whims." 

808. General properties of sugar as produced from various substances. 

26* 



306 SUGAR. 

combinations with metallic oxides; lime, baryta or strontia 
boiled with sugar make it bitter, astringent, and uncrystaliza- 
ble. By adding a sufficient quantity of an acid to neutralize 
the oxide, the sugar resumes its properties. 

809. The results in the decomposition of sugar being found to vary, it was 
at length discovered that its constituent principles varied in some degree in 
different vegetables ; thus the sugar of the cane affords more carbon than 
that of the grape. According to Gay Lussac the sugar of the cane is, in 
weight, composed of 

Carbon 42.47 

Oxygen 50.63 

Hydrogen 6.90 

100.00 
According to Liebig; Car. 12, Hyd. 11, Ox. 12=179 
Sugar of the grape was found to consist of 

Carbon 36.71 

Oxygen 56.51 

Hydrogen 6.78 

100.00 
The specific gravity of sugar is about 1.6. 

810. The sugar cane is the arundo saccharifera of botanists. 
This plant furnishes the greater part of the sugar of commerce. 
Although sugar was manufactured in India in the days of Alex- 
ander the Great, who is said to have brought the knowledge of 
it to Macedon, yet it was scarcely used in Europe, except in 
medicine, until the discovery of the West Indies, where the most 
extensive sugar manufactories now exist. 

Sugar is obtained from the expressed juice of the sugar cane, by slow 
boiling, during which process the aqueous particles evaporate. Lime water 
is then added to the liquor when boiling, to neutralize the oxalic, and other 
vegetable acids, and to separate extractive matters and other impurities, 
which, uniting with the lime, rise and form a thick scum on the surface ; the 
liquor below, is drawn off, by means of a syphon, into large shallow vessels, 
where an imperfect crystalization takes place. 

811. From the sap of the sugar-maple tree Acer saccharinum, 
is manufactured, to a considerable extent, a valuable domestic 
sugar in many of the northern United States. 

Incisions are made in the trees at that season of the year when the sap 
runs most abundantly ; this is in early spring, with the first warm beams of 
the sun. The sap of the maple is about one sixth as rich as the juice of the 
cane; four pounds of maple sap yielding one pound of sugar. When suita- 
bly evaporated, by boiling in large kettles, and permitted to cool, it forms a 
granular solid mass. This may be purified so as to resemble loaf sugar, in 
whiteness and fineness ; but is generally used in a less refined state. The 
maple juice boiled down to a consistence somewhat less than common West 

809. Constituent principles of sugar, &c. Gay Lussac's and Liebig's 
analysis. 

810. Sugar cane. Manufacture of sugar. 

811. Maple Sugar. Manufacture of Maple Sugar. 



SUGAR. 307 

India molasses is used for similar purposes ; and when evaporated to a thick 
syrup, resembling liquid honey, it is sometimes used for the table, as a sub- 
stitute for sweetmeats. 

812. The beet root is found to be rich in sugar. In France, are many 
large manufactories of this article. Count Chaptal, a peer of France, a 
theoretical, and practical Chemist, and farmer, says, " from twelve years 
experience I have learned in the first place that the sugar extracted from 
beets differs from that of the sugar cane neither in color, taste, nor crys- 
talization ; and in the second place that the manufacture of this kind of 
sugar can compete, advantageously with that of the sugar cane.* 

813. Many other succulent roots, besides the beet, furnish 
sugar, as the onion, parsnip and carrot. 

Sugar of grapes, of figs and other ripe fruits contains more or 
less of the peculiar flavor of the fruit derived from other prin- 
ciples. It does not crystalize in regular forms, and it is less 
sweet than the sugar from the cane. Sugar of mushrooms crys- 
talizes in four-sided prisms ; its taste is not pleasant. Sugar 
of starch is made by forming a paste with starcfe and water and 
allowing it to stand for some time. Sulphuric acid converts 
starch into sugar. De Saussure found the weight of sugar 
formed was considerably more than that of the starch employed, 
from whence he inferred that a portion of the water becomes 
solidified, that the sugar of starch was consequently only a 
combination of sugar with hydrogen and oxygen in the neces- 
sary proportions to form water, and that the sulphuric acid had 
no other influence than to increase the fluidity of the aqueous 
solution of starch. 

814. Manna (from a Syrian word mano a gift, being the food given by God 
to the Israelites), exists in the sap of the ash, Fraxinus ornus, in the celery 
and beet plant. It is sweet and crystalizable like sugar, but it owes its 
sweetness to a distinct principle called mannite. This principle differs from 
sugar in not fomenting with water and yeast, of course it produces no alco- 
hol. 

Honey is composed of two kinds of sugar, the one liquid and uncrystaliza- 
ble, the other analogous to the sugar of grapes and crystalizable ; these, 
with mucilage, and an aromatic principle, constitute all the varieties of 
honey. By mixing honey with alcohol, the liquid sugar may be obtained by 
pressing the solution through a strainer, while the crystalizable principle 
remains solid. Honey is prepared in the stomach of the bee, from the vis- 
cous juice and sugar which this insect collects from the nectaries of flow- 
ers ; after remaining a time in this laboratory it is deposited in the cavities 
of the honey comb. Honey varies in quality according to the different 

* See ChaptaPs " agricultural Chemistry," for a detailed account of the 
mode of cultivating the beet root, and conducting the beet sugar manufac- 
ture. 

812. Sugar of beets. Chaptal's opinions upon the manufacture of beet 
sugar. 

813. Other roots which furnish sugar. Sugar of grapes, figs, &c. Sugar 
of mushrooms. Sugar of starch. 

814. Manna. Honey. Sugar of liquorice. 



308 STARCH. 

plants which furnish the materials. That which is obtained from the flow- 
ers of the tobacco, stramonium, and others of the same natural family, is 
poisonous. The honey of Mount Hymettus und Mount Ida in Greece was 
celebrated in ancient times for its beauty and excellence. The honey fur- 
nished by labiate plants, as the thyme, balm, &c, is of the best kind. Honey 
is used as food and medicine. When united with the vinegar it forms oxy- 
mel. Thus the common preparation of squills is called the oxymel of squills.* 
Dissolved in water, honey ferments, and forms a liquor called hydromel or 
metheglen, a pleasant but intoxicating beverage. 

Sugar of liquorice. The substance called liquorice is from the root of a 
plant, the Glycirrhiza glabra ; its sweet principle seems to be of a peculiar 
kind. It resembles amber in its appearance and inflammability. 

815. Starch, is one of the most abundant proximate principles 
in nature, existing in the stems, leaves, roots and seeds of plants. 
When pure it is a white powder, insipid, inodorous, insoluble in 
cold water, alcohol and ether, but soluble in boiling water. This 
solution on cooling takes the form of a jelly, in which state it is 
used by the laundress for starching linen. Hot sulphuric acid 
transforms starch into sugar, capable of yielding alcohol by fer- 
mentation. Nitric acid changes it into malic and oxalic acids. 
Iodine furnishes the best test for starch, forming with it com- 
pounds of a blue color. The principle deduced from this fact is 
applied in the arts to discover whether goods owe their fine- 
ness to the texture of the material or to a finish of starch ; 
in the latter case, a drop of the solution of iodine produces a 
blue spot. 

816. According to Gay Lussac and Thenard, starch is composed of 
43.55 parts of Carbon. 
49.68 " " Oxygen. 
6.77 " " Hydrogen. 

Starch is usually obtained by gratin? or bruising the substances which 
contain it, and washing the product with pure water. Its specific gravity 
beins greater than that of water, the starch is soon deposited in the form of 
a white mass, which, when dry, is a soft powder. If a piece of dough or 
wheat flour be enclosed in a linen bag, and pressed with the hand while a 
current of cold water is poured on, the starch or farina will be washed out 
mechanically and subside at the bottom of the vessel, while the gluten of the 
flour is left pure in the bag, and saccharine matter and mucilage are in solu- 
tion. Heat produces with starch peculiar effects ; thus, when dry starch is 
heated a little above 112°, it becomes soluble in cold water, and its odor 
resembles that of baked bread. The action of boiling water on starch, as 
prepared for starching muslin, produces a similar change of properties. By 
continued heat, and careful evaporation a transparent mass is obtained, so- 

* That is, oxymel combined with the juices of a bulbous plant, the Scilla 
maratima or squills. 

815. Abundance of starch in vegetables. Properties. Action of other 
bodies upon it. 

816. Constituent elements of starch. Modes of obtaining starch. Action 
of heat and of boiling water upon starch. 



GUM. 309 

luble in cold water, and resembling horn, this is called amidine*. Starch 
"when exposed to a greater heat than sufficient to produce amidine is con- 
verted into a substance called gum, and in this state is used by calico prin- 
ters. 

817. We have seen that the constitution of starch differs lit- 
tle from that of sugar, and that the former may be easily con- 
creted into the latter. This change takes place in the germina- 
tion of seeds, in the process of malting barley, and in vegeta- 
bles that have been frozen under certain circumstances: thus 
apples, which have been exposed to the air during severe frosts, 
acquire a peculiar sweetish taste. 

818. Of the various kinds of starch, those which are obtained from the 
flour of different kinds of grain, from the potato, and green Indian corn are 
used in the laundrey for starching linen and muslin. The Indian arrow- 
root, (Maranta arundinaeca,) Sago (from the pith of the Cycas circinalis^) 
Tapioca, and Cassava, (from the root of a plant,) have the properties of pure 
starch. They are all highly nutritious and valuable as food for the sick. 

GUM AND MUCILAGE. 

819. Gum is an aDundant product of vegetables. It is un- 
crystalizable, colorless, inodorous, insoluble in alcohol, and so- 
luble in water with which it forms a gelatinous compound called 
mucilage. It cannot be made to pass through the vinous fermen- 
tation. Nitric acid changes it to mucic acid. Gum or mucilage 
is found in all the parts of herbaceous plants, in many roots, 
and in all fruits. Many trees, particularly those whose fruit is 
of the drupef kind, secrete large portions of gum. 

820. The principal gums are. 

1. Common gum, obtained from the peach, plumb, cherry tree, 
&c. 2. Gum Arabic, which flows naturally from the acacia or 
mimosa of Egypt, Arabia and other warm countries ; this, with 
water, forms a clear, transparent mucilage. 3. Gum Senegal 
resembles Gum Arabic except that it is exported in much 
larger pieces. 4. Gum tragacanth, from the Astragalus traga- 
cantha, a shrub of Syria ; and of the islands of the Levant. 
These are all useful in medicine and the arts ; and in some 
countries they are used as food. 

* So called by the French Chemists from amidon, the French name for 
starch. 

f Having a kernel enclosed within a pulpy substance, as the cherry, plum, 
and peach. 

817. Conversion of starch into sugar. 

818. Uses of starch. 

819. General properties of gum, &c. 

820. The principal gums. Uses of these gums. 



310 WOOD, LIGNIA, &C. 

821. Flax-seed, the fruit and seeds of the quince, the bark of 
the slippery elm, and the different species of mallows, all afford 
mucilage when boiled in water. When evaporated to the thick- 
ness of syrup the gum is precipitated by alcohol. Mucilage 
may be considered as an aqueous solution of gum, existing 
naturally in ripe fruits, and the leaves and roots of some plants, 
and formed by dissolving gum in water. Mucilage soon be- 
comes sour on exposure to the air, owing to the formation of 
acetic acid j and in time this change takes place without access 
of air, which must be owing to the new arrangement of its con- 
stituent principles. 100 parts of gum arabic have been found 
to consist of. 

42.23 parts of Carbon. 
50.84 " " Oxygen. 
6.93 " " Hydrogen. 

100.00. 
Vegetable jelly, such as is obtained from the currant, quince 
grape, &c, is mucilage combined with different vegetable acids. 

WOOD, LIGNIA, OR WOODY FIBRE. 

822. This is the basis or skeleton of vegetable substances, 
and the most abundant of all the proximate or vegetable princi- 
ples forming about 96 per cent of the different kinds of wood. 
The woody or hard substance of plants contains, in its inter- 
stices the sap, and other peculiar principles, as the volatile oils, 
gums, resins, sugar, Sec. This substance is found in every part 
of the plant, the root, the stem, Jeaf, fruit and even the flower. 
In the dry state it may be seen in the shells of almonds and 
many other nuts, even the soft petals of the rose, when deprived 
of their essential oils, mucilage and other extractive matter, will 
be found reduced to this hard insoluble substance. 

Ligniajov chemical purposes, is usually obtained from saw-dust, because 
wood thus minutely divided, is in a favorable state to be acted upon by the 
agents which are required to purify it of all foreign matter. Saw-dust is 
first digested in alcohol, to dissolve the resinous part, afterwards in water 
which dissolves some salts and extractive matter, then with weak muriatic 
acid, which attacks salts that are insoluble in water, particularly the carbo- 
nate and phosphate of lime. Lignia is white, insipid, inodorous, and speci- 
fically heavier than water. 

Sulphuric acid decomposes lignia ; changing it first into a gum-like sub- 
stance, which, on being boiled, becomes sugar. According to Beaconnot 
all substances which contain lignia, as saw-dust, straw, bark, and linen, 

821. Mucilage. Composition of gum arabic. Vegetable jelly. 

822. Abundance of woody fibre, &c. Lignia for chemical purposes, ho* 
obtained ? Properties, &c. Products of the decomposition of wood, by 
heating in close vessels. Bread made from saw-dust, &c. 



COLORING MATTER, &C. 311 

may be converted to sugar. In heating wood in close vessels, acetic (pyro- 
ligneous) acid and volatile products are obtained. Among these, ispyroxy- 
lic spirit. It is found that bread may be made from saw-dust, bark, rags, 
&c, by converting these substances into lignia. The latter, when heated 
in an oven, smells like meal or flour of Indian corn". It ferments with leaven, 
and affords a spongy, nutricious bread. The same flour of wood, when 
boiled, affords a jelly like that of starch. 

COMPOUNDS WHICH ARE NOT CONSIDERED AS BELONGING TO THE 

PRECEDING DIVISIONS OF VEGETABLE PRINCIPLES J AS 

COLORING MATTER, TANNIN, GLUTEN, &C. 

823. Coloring matter. Vegetable coloring matter is found at- 
tached to some proximate principle, as mucilage, farina, resin or 
extractive matter ; and its solubility depends on the nature of 
the principle with which it is associated. Coloring matter 
cannot, therefore, be considered as itself a proximate principle. 
Color is a secondary property, dependant on the peculiar ar- 
rangement of atoms, and of course affected by chemical changes. 
Thus, we have saen in the course of our experiments, color of 
bodies changing with new combinations ; a colorless acid trans- 
forming the blue infusions of flowers to a brilliant red, and a 
colorless alkali changing the same blue infusion, to a green 
color. The process of dyeing, depends on chemical principles, 
but the details of the subject belong to the arts rather than to 
science. 

The coloring matter resides in various parts of plants. In 
some, it is in the flower, in others, in the bark, or the leaves, 
wood, or root. It is soluble by various agents according to the 
nature of the proximate principle with which it is associated ; 
thus some colors are obtained by means of alcohol, othe»s by 
water, others by acids, and others by the essential oils. Most 
vegetable colors are decomposed by exposing to the sun, and 
all by the agency of chlorine. 

824. Several of the metallic oxides, and especially alumina and the oxides 
of iron and tin form with coloring matter insoluble compounds, to which the 
name of lakes is applied. Lakes are commonly obtained by mixing alum or 
pure muriate of tin with a colored solution, and thus, by means of an alkali, 
precipitating the oxide, which unites with the color at the moment of separa- 
tion. In this property is founded many of the processes in dyeing and calico- 
printing. The art of the dyer consists in giving a uniform and permanent color 
to cloth. 

823. Coloring matter not a proximate principle, &c. Situation of the 
coloring matter in plants. Means of obtaining these colors. Decomposi- 
tion of vegetable colors. 

824. Compounds with coloring matter, called lakes, &c. Setting of 
colors. The use of a mordant. Substantive and adjective colors. Sub- 
stances which change the hue of coloring matter, &c. 



312 BLUE. 

The setting of colors depends on a chemical affinity between the dye, 
and the material with which it unites. To produce this affinity the agency 
of a third substance is often required, which is called a basis or mordant.* 
This unites the coloring matter to the cloth by means of an affinity for both. 
The most important bases or mordants used in dyeing, are alumina, and the 
oxides of tin and iron ; but many others are useful, as alum, copperas, sugar 
of lead, muriate of tin, blue vitriol, &c. 

Colors that adhere to the cloth without the intervention of bases are call- 
ed substantive colors, while those which only form a transient union with 
cloth, unless fixed by a third substance, are called adjective colors. 

Besides bases to fix the coloring matter, various chemical agents are em- 
ployed to alter the shade or hue of colors; thus the hydrochlorate of tin 
changes the crimson of cochineal to a brilliant scarlet. Alum changes the 
dull red of madder to a bright crimson. The attraction both of coloring 
matter and mordants for wool and silk, is much greater than for cotton ; 
thus we find the most brilliant and permanent hues in woolen and silken 
stuffs. All the hues obtained in dyeing, may be produced by four primary 
colors, blue, red, yellow, and black. 

825. Blue. The only vegetable substance used for dyeing 
blue is indigo. This is obtained from several species of the In- 
digofera, and has been found in small quantities, in some other 
plants. The indigo plant is a product of warm climates. 

The leaves are fermented with water in large tubs ; the liquor becomes 
acid, and covered with irised pellicles. It is then drained, and mixed with 
lime water. A deposit is formed, which when washed, and dried, is the 
indigo of commerce. In order to obtain perfectly pure indigo, it should be 
heated in a closely covered silver crucible. It soon volatilizes and deposits 
purple crystals. 

Pure indigo has neither taste nor odor ; its color is a rich 
blue, with a shade of purple. It does not dissolve in water, al- 
cohol, or ether. Strong sulpuric acid dissolves it, forming a 
sulphate of indigo, which is employed for giving the color called 
Saxony blue. Where indigo is deoxygenated it loses its fine 
colcxr^ becomes yellow, and is easily dissolved in slightly alkaline 
water ; if this solution be agitated in contact with the atmos- 
phere, the indigo acquires oxygen, and becomes blue. 

The dyer's blue-vat is made by mixing indigo with an equal weight of 
green sulphate of iron, twice its weight of lime, and boiling the mixture in 
waterf. The protoxide of iron precipitated by lime, gradually deoxydizes 
the indigo, and a yellow solution is obtained. Cloth wet in this liquid, and 
exposed to the air, becomes green, and then blue by the union of the deoxy- 
dized indigo with the oxygen of the air ; and the blue indigo being now 
chemically united with the fibre of the cloth, a permanent color is obtained. 

A white substance called indogene has been obtained by depriving indigo 
of its oxygen ; it rapidly changes to blue on exposure to the oxygen of the air. 

* From mordeo to bite, corrode or fasten upon. 

f In the domestic blue dye the ammonia of urine is the solvent of indigo. 

825. Indigo, how obtained from the plant ? Properties of indigo. Effects 
of deoxygenating indigo. Blue-vat of the dyer, &c. Effect of air upon 
cloth wet in a solution of deoxydized indigo. 



YELLOW. 313 

826. Red. Among the red coloring matters are Madder, Cochineal, Archil 
or Litmus, Logwood, Brazil Wood and Safflower. 

Madder is the root of the Rubia tinctorum. It is used in dyeing the 
Turkey-red, and by the aid of proper mordants, may produce not only the 
various hues of red ; but purple and black. This is seen when calico 
stamped with different mordants is wet in the madder dye. The coloring 
matter of madder is supposed to have been obtained in a pure state by some 
of the French chemists in the form of brilliant red, needle-shaped crystals. 

Cochineal, though found on the leaves and branches of the cactus plant, 
is an animal substance, deposited by an insect which feeds upon it. It is a 
fugitive dye when mixed with water only ; but becomes fixed by alumina, 
or the oxide of tin. Its natural crimson color is changed to scarlet by the 
permuriate of tin, or the bitartrate of potassa, (cream of tartar.) Carmine 
is made of cochineal and alumina. 

Litmus, archil, or turnsol is prepared from the Lichen roccella, a plant 
which grows in the Canary, and Cape de Verd islands. The color of the 
linchen is red; but in preparing litmus by means of fermentation with an 
alkaline substance, it receives a blue tint. This preparation is affected by 
the weakest acids, and is, therefore much used as a chemical test. Paper 
tinted wiih litmus is called litmus paper, and furnishes a convenient mode 
of using this as a chemical test. Litmus paper, when reddened with an 
acid.becomes blue in an alkaline solution. 

Logwood is a heavy compact wood from the Ha ematoxylum* campechianum, 
a plant which grows in South America. Its coloring matter has been ob- 
tained in crystals called hematine. Logwood affords a red, fugitive color, 
but is chiefly used for black dyes, which are fixed or set with iron ; copperas 
(sulphate of iron) is chiefly used for this purpose. 

Brazil Wood is from the Caesalpina echinata a large tree of Brazil. 

Safflower is the dried flower of the Carthamus tinclorius, an unusual plant 
of the countries bordering on the Mediterranean. This is the exotic com- 
pound flower of our gardens, known by the name, Saffron, although the 
crocus is the true Saffron. The flowers of the Carthamus or false saffron 
are yellow ; but according to Thenard, repeated washing dissolves the yel- 
low coloring matter, leaving the red which was combined with it. This 
article gives a variety of shades of red, from that of the damask rose to the 
cherry. They are fugitive colors though very brilliant. Rouge is prepared 
from this substance. 

827. Yellow. Of yellow dyes the principal are the American 
walnut, tumeric, fustic, saffron, sumach, and quercitron. These 
like the red dyes are all adjective colors. 

The bark of the walnut, and the butternut afford a yellow dye, which, 
with iron becomes brown. Turmeric is the root of an East Indian plant, 
the Cucurma longa. Paper stained with an infusion of this dye is called 
turmeric or cucurma paper ; it is stained brown by an alkali, for which 
reason it is used as a chemical test. Fustic is obtained from the West In- 
dies ; it is the wood of the Morus tinctoria. Saffron is from the Crocus sati- 
vus. With water and alcohol it forms a bright yellow, which sulphuric 

* This name is from the Greek haima, blood, in reference to the red color 
of the wood. 

826. Red Colors. Madder. Cochineal. Carmine. Litmus. Logwood. 
Brazil Wood. Safflower. Rouge. 

827. Yellow dyes. 

27 



314 TANNIN. 

acid changes blue, then lilac, and nitric acid gives it a green shade. Sv- 
mach. The bark of the different species of the Rhus, furnishes a yellow dye. 
This was formerly exported in large quantities from America to England. 
Quercitron is the hark of the common black oak of this country. A decoc- 
tion of this bark, gives a bright yellow dye with a basis of alumina ; with 
oxide of tin all the shades of yellow from pale brown to deep orange. With 
indigo it forms a green color, and with oxide of iron a drab color. Jlnnotta, 
improperly called otter, is obtained from the seeds of a plant of Cayenne, the 
Bixa orellana ; it is sometimes used to heighten the color of cheese, and is 
much used in domestic dyeing. 

Carthamus tinctorius so common in our gardens furnishes a fine though 
fading straw color. It is probable lhat the foreign species of carthamus 
from which saffron is obtained, differs from the saffron of our gardens. 

828. Black dyes, as writing ink, &c. consist of the salts of 
iron with gallic acid and tannin ; astringent barks, such as 
maple, oak, &c. afford these two substances ; secretions of such 
barks with copperas (sulphate of iron,) will therefore color 
black. Gall-nuts are often used instead of bark to furnish gallic 
acid and tannin. 

There are various mineral dyes as orpiment, the chromates, and Prussian 
blue; the latter is partly mineral, and partly, an animal compound. There 
are .various modes of applying the colors in dyeing cloth of different kinds. 
In general, the cloth is passed through a decoction of the coloring matter, 
and then of the mordant; the latter seems to perform the same office in 
preserving a union between the coloring matter and the texture of the cloth, 
as the alkali which affects a combination between oil and water. In calico 
printing " The mordant thickened with sum or flour, is applied to the cloth 
by means of blocks or engraved copper cylinders. The cloth is then passed 
through a decoction of the color which adheres only to the spots impregna- 
ted with the mordant, and is easily discharged, by washing. To preserve 
certain parts white, they are occasionally covered with wax, tallow or pipe 
clay, and sometimes the color is discharged from particular parts by chlo- 
rine."—^. 



TANNIN. 

829. To the proximate principle called tannin, vegetables owe 
their astringent properties. This principle exists in large pro- 
portions in the bark of certain trees, in the gall-nut, and in the 
leaves of the tea-plant. 

The most remarkable property of tannin is that of forming 
with many animal substances, particularly gelatine, a tough 
insoluble and imputrescent compound. Thus the skins of 
animals, which are mostly composed of gelatine, by being 
soaked in the tan-vat, (a decoction of astringent bark,) are con- 
verted into leather, which is not only necessary to the comfort, 
and health of man, but in various ways contributes to his con 

828. Mineral dyes. Various modes of applying colors, &c. 

829. Cause of the astringent properties of plants, &c. Action of tannio 
with gelatine. Leather. Action of tannin on the salts of iron. 



GLUTEN. 315 

venience, and is of extensive use in the arts of civilized life. 
Another important property of tannin is its action on the salts 
of iron, which it preciptates, producing in combination with 
gallic acid, ink and black dyes. 

830. Pure tannin is obtained with difficulty owing to its tendency to form 
combinations with the principles with which it is associated. It may be 
precipitated from an infusion of nut-galls by various re-agents ; as sulphuric 
and muriatic acids, carbonate of potassa, and muriate of tin. The precipi- 
tate of tannin is combined with other matters, which are separated by va- 
rious complicated methods. Some gallic acid and extractive matter will 
often be found after the most careful preparation. Proust recommends pre- 
paring tannin by precipitating it from an infusion of nut-galls, by muriate 
of tin, washing the precipitate, and passing over it a current of sulphuric 
hydrogen, filtering and evaporating the liquor. Tannin tolerably pure may 
be obtained by precipitating it from an infusion of nut-galls, with lime-water. 
Pure tannin is without color, very soluble in water, but insoluble in per- 
fectly pure alcohol. The acids, except the acetic, precipitates it from its 
solution in water. Tannin is most abundant in the inner layers of the bark 
of hemlock, oak, chestnut and birch. 

831. Artificial tannin, a substance resembling tannin may be produced by 
the action of diluted nitric acid on oil, or indigo ; or by the diluted sulphu- 
ric acid with the resins, or charcoal. A solution is thus obtained which, 
when evaporated to dryness, produces a brown, fusible substance, soluble 
in water, and insoluble in alcohol, and which exhibits, with a salt of iron, 
and a solution of gelatine the same changes as natural tannin. Lagrange 
asserts that tannin changes into gallic acid by the absorption of oxygen. 

GLUTEN, YEAST j VEGETABLE ALBUMEN. 

32. Gluten is obtained in the process for the separating the 
fecula or starch from wheat flower by washing ; the albumen 
and sugar lodged in the interstices of the gluten are dissolved 
and carried off with the fecula; the gluten is pure when it no 
longer disturbs the transparency of water by washing. It is of 
a grayish white color, soft, viscous, very tenacious, and elastic. 
When dried it becomes brown, and has a glossy brittleness. 
Exposed to the moist air it swells, putrifies and diffuses an 
odor, like that of cheese. It does not dissolve in cold water or 
alcohol ; warm water destroys its tenacity and elasticity, but 
without dissolving it. It is soluble in most of the vegetable, 
and some of the mineral acids. Charcoal, sulphuric and nitric 
acids act upon it, as upon most animal substances. 

833. Taddei, an Italian Chemist does not regard gluten as a proximate 
principle, but as formed of two such principles, which he calls gliadine,* 

* From the Greek glia, gluten. 

830. Extraction of pure tannin. Properties of pure tannin. 

831. Artificial tannin. 

832. Manner of obtaining gluten. Its properties, &c. 

833. Gliadine and zimome. Test for zimome and albumen in flour. 



316 YEAST. 

and zimome* Berzelius, however, supposes the gliadine to be modified 
giuten, and the zimome to be albumen. The Italian Chemist, in his re- 
searches, discovered that the powder of gum guaicum afforded a delicate 
test for the zimome ; as, when rubbed in a mortar with this substance in 
a moist state, it strikes a fine blue color. This test is found equally good 
to shew when flour contains the due proportion of albumen or gluten ; it is 
kneaded into the flour, which, if good, assumes a blue color. But if the 
flower be bad, owing to the spontaneous decomposition of gluten, the blue 
tint is scarcely visible. 

834. Gluten appears to promote fermentation. The action of 
yeast has been ascribed to its presence. It is favorable to 
animal nutrition. Thus bread is emphatically called the "staff 
of life." The different kinds of grain contain a large proportion 
of gluten, but wheat more than any other. Thegluten in wheat 
flour, on account of its elastic, and viscous nature, is favorable 
to the formation of light bread. The carbonic acid gas which 
is disengaged during the fermation, being detained by the gluten, 
expands if, and causes the pores which appear in light, wheaten 
bread. Rye bread can never be made so light as wheat, because 
rye contains little gluten ; and Indian meal without intermixture 
with some other substance can scarcely be 7'aisedat all by yeast. 

835. Potatoes contain no gluten, but much farina, and may 
be mixed with wheat flower in making bread ; but, if added in 
too large proportion, the bread will be heavy, because, for want 
of sufficient gluten to retain the gas of fermentation, the latter 
passes off in the atmosphere; and if, as supposed, gluten assists 
fermentation, there will be the less gas disengaged. This sub- 
stance was discovered by Beccaria an Italian chemist, who, 
from its analogy to glue, both in its viscid properties, and its 
tendency to putrefy, like animal substances, called it gluten. 

836. Yeast is a viscous, frothy substance which rises to the 
surface of fermenting liquors. f When liquor is fermenting, 
the yeast rises to the surface, with the gas it generates ; but, 
afterwards, becomes specifically heavier than the liquor, and 
sinks. 

The yeast of breweries, and distilleries is best for raising bread. But 
when this cannot be obtained yeast may be prepared by adding a small quan- 
tity of ferment to a decoction of hops, made of proper consistency with rye 
or wheat flour. Boiling water, or heat, equivalent to it, destroys the fer- 

* From zume, a ferment or yeast. 

t Vulgarly called emptins, as when beer is drawn off, it is found at the 
bottom, or in the emptyings of the cask. 

834. Gluten favorable to fermentation, &c. Rye flour and Indian meal 
contain little gluten. 

835. Effect of mixing potatoes with wheat flour in making bread. Dis- 
covery of gluten and derivation of the name. 

836. Yeast, &c. Domestic yeast. Dried yeast. Effect of heat on yeast. 



PIPERIN. 317 

meriting power of yeast. The cause of its action in producing fermentation 
has not been discovered. By distillation yeast affords carbon, hydrogen, 
and some nitrogen ; it resembles gluten in its composition. 

b37. Vegetable Alhumen, a substance resembling animal albu- 
men, and especially in its property of coagulating with heat, 
has been discovered in the almond, and some other oily seeds. 
It contains nitrogen, and when exposed to the moist air, under- 
goes the putrefactive fermentation, emitting an offensive odor 
like that of old cheese, and disengaging ammonia. Vegetable 
albumen and gluten appear to form a connecting link between 
vegetable and animal substances. 

838. There are many vegetable principles which have not yet received 
a classification, owing to their not having been sufficiently studied, or to 
some obscurity in the nature of their constitution. 

Jlsparagin has been discovered in the juice of the asparagus, with an acid 
called espartic ; which, by decomposition, affords ammonia, proving that it 
contains nitrogen ; it exhibits neither acid nor alkaline properties, it is 
found in the juice of liquorice, and the Allhea officinalis or marsh-mallows. 
Fungin is that portion of the fleshy part of the mushroom which remains after 
removing every thing soluble, by digesting in alcohol and alkaline water ; 
it is very nutritious, has a smell like bread, but appears to resemble animal 
matter, in its composition. Legumin is extracted from the pulp of peas ; its 
solution gives, with sulphate of lime, a dense coagulum, which is supposed 
to explain why peas boiled in hard water, or that containing a salt of lime, 
become hard ; peas and beans are found to consist of 18.40 per cent of le- 
gumin with 42.58 of starch, 8 of water, 4 of nitric acid, and 8 animalized 
matter, &.c. Ulmin was discovered by Vauquelin in the brown matter which 
exudes from the elm, (Ulmus), Braconnot found it in turf and mould ; it has 
been regarded by some Chemists as an acid, and called ulmic acid ; ammo- 
nia and oxygen change gallic acid into alumina. 

Caffein is a white, crystaline matter extracted from coffee ; Pelletier re- 
garded it as a salifiable base, but it neither affects blue vegetable colors, 
nor combines with acids. Bassorin was first extracted from gum Bassora, 
a substance resembling gum tragacanth, and imported from Bassora in Asia ; 
it has been found in assafcetida, and some other resinous plants. Cathartin 
is a substance which has been obtained from senna and is supposed to con- 
lain the cathartic principle of that plant. Suberin is a name applied by 
Chevreul to the cellular tissue of the cork tree (Quercus Suber } ) which he 
supposes to be a proximate principle ; the cells of this substance are filled 
with astringent, coloring, and resinous matter; the latter, Chevreul called 
cerine. By the action of nitxuc acid, suberin changes to suberic acid. Lu- 
pulin is obtained from the membraneous scales of the pistilate flower of the 
hop. It is very bitter, and soluble in water and alcohol. 

Piperin is procured from black pepper (piper nigrum) ; it has some of 
the stimulating px-operties of pepper ; these being found to reside in a vola- 
tile oil. Oliville extracted by Pelletier from the gum of the olive tree, has 
a bitter and aromatic taste. Rhubarbarin is a name given to an extract of 

837. Vegetable albumen. 

838. Asparagin. Fungin. Legumin. Ulmin. Caffein. Bassorin. Ca- 
thartin. Suberin. Lupulin. Piperin. Oliville. Rheubarbarin and Rein. 
Sarcocoll. Pollenin and Medullin. Colocynthis. Polycroite. Nicotin. 
Dahline and Inulin. 

27* 



318 CHLOROPHILE. 

the medicinal rhubarb, supposed to contain its active principle. Sarcocoll, 
from a plant of Ethiopia and Persia called the Penaa sarcocolla, is imported 
in small grains, resembling gum arabic. It forms mucilage with water; it 
differs from gum in being soluble in alcohol, and by being precipitated by 
tannin from its aqueous solution. It has a sweetish taste, resembling that 
of liquorice. Pollenin. The pollen of tulips was found by Professor John, 
to constitute a peculiar principle, of a very insoluble nature, highly com- 
bustible, burning with a rapid darting flame. It has been used in theatres 
for artificial lightning. The same chemist discovered a peculiar substance 
in the pith or medulla of the Sunflower, which he called medullin. Thig 
substance yields ammonia by destructive distillation. Colocynthin, is a name 
given by Vauquelin, to a bitter, resinous extract from the colocynth in which 
the medicinal properties of the plant reside. 

Polycroite is obtained from the flowers of ths saffron (Crocus sativus.) It 
is the coloring matter of the saffron ; it is named from polus, many, and 
kroma color, on account of its producing different colors with acids. .Nitric 
acid gives it a green color, which disappears on diluting it with water. Sul- 
phuric acid, at first, changes it blue, which color gradually passes to violet. 
Nicotin is a peculiar principle obtained by Vauquelin from tobacco (Nico- 
tiana tabaccum.) It has the smell and taste of the plant, is volatile and 
poisonous. Professor Silliman says, " The empyreumatic oil of tobacco, 
disengaged in smoking, is doubtless nicotin modified and perhaps rendered 
more noxious by the heat."* Dahlim exists in the tubercles of the Dahlia. 
It resembles starch in most of its properties. Dahline exists with inulin in 
the Jerusalem artichoke, both substances are varieties of fecula or starch, 
and are therefore nutritious. The Dahlia root, if as easily cultivated as the 
potatoe, might, therefore form a valuable aliment. 

839. Citlorophile is a name given to the green coloring matter of plants, 
formerly called green fecula of plants ; it is obtained by coagulating the green 
juice of plants with heat, and purifying the coagulum with water and alco- 
hol; it is a deep-green, resinous substance; from some late discoveries it 
appeai-s that the resin may be removed by ether, after which, according to 
some chemists, the coloring matter will be left pure.f Bitter principle, a 
term formerly applied to a supposed peculiar substance which caused the 
bitterness of plants ; but it is found that different principles indifferent 
plants produce this effect ; thus the bitter principle of the hop is owing to 
lupulin, that of opium to morphia, &c. Extractive matter, a term formerly 
supposed to refer to a peculiar principle ; but it is vague and indefinite, 
since no such distinct principle has ever been obtained. When vegetable 
substances are macerated in water, there usually remains, after removing 
the proximate principle, something which seems to belong to none of these 
principles ; and this has been called extractive matter, a convenient term, 
which expresses a mixture of different principles, or the residuum of vege- 
table infusions and decoctions. 

* " As a source of refreshment and pleasure to man, tobacco ought to be 
universally proscribed ; it should be retained only as a means of destroying 
insects and vermin, and as a medicine, which, in its internal use is so vio- 
lent and dangerous, that the proper occasions for emyloying it must be " few 
and far between." — Sil. El. of C hem. Vol. 2. p. 509. 

f What can those chemists mean who talk about a pure coloring matter, 
since color is itself a mere secondary property of matter, and cannot exist 
separate from a colored body ? Can they expect to obtain a substance of 
which they can say, ' this is pure color ?' or, " pure coloring matter V 

839. Chlorophile. Bitter principle. Extractive matter. 



FERMENTATION. 319 

CHAPTER XXXV. 

FERMENTATION. 

840. By fermentation is understood, a spontaneous change 
which takes place in substances; their elements disunite, com- 
bine in other proportions, and give rise to compounds, differing 
wholly from any which had originally existed in the fermenting 
mass. There are various kinds of fermentation ; as the panary 
which produces bread, the saccharine which affords sugar, the 
vinous in which sugar is converted into alcohol, the acetous 
which results in vinegar, and the putrefactive which results in 
the entire dissolution of organic matter. 

841. Panary* or bread fermentation. It is evident that bread, 
or even raised dough, differs essentially from a mixture of flour 
and water which has not undergone a process of fermentation. 
Besides the porous and spongy texture which distinguishes the 
former, it has a peculiar pungent odor, so that on opening a 
mass of thoroughly raised dough, a peculiar effluvia issues, 
scarcely less penetrating than that of ammonia. Dough is not 
only enlarged in bulk by fermentation, but, when subjected to 
the heat of the oven, it swells to a still greater bulk, and ap- 
pears in the form of light bread $ while dough that has not pas- 
sed through the fermenting process does not rise in the oven, 
and would, if baked, present a compact, heavy, insipid and in- 
digestible mass. 

842. It is to gluten that flour owes its property of forming a 
paste with water. Paste is merely a viscous and elastic tissue 
of gluten, the cells of which are filled with starch, mucilage, 
sugar, &c. This being understood, we can readily conceive, 
that to gluten, paste owes its property of becoming light when 
mixed with yeast. The yeast acting upon the farina or starch 
of the flour converts it into a gummy, sugar-like substance. 
This saccharine fermentation is the first stage in the process. 
The change of sugar into alcohol and carbonic acid next takes 
place, and this vinous fermentation is the second stage. If the 
process is suffered to go on, alcohol isconverted into active acid 
or vinegar, and this acetous fermentation works a third stage. 

* From the Latin pairis, bread. 

840. What is meant by fermentation ? Different kinds of fermentation. 

841. Changes effected in Hour by means of the panary fermentation. 

842. Importance of gluten in flour. Stages in panary fermentation. 
Cause of the porous texture of bread. 



320 FERMENTATION. 

At the second or vinous stage of fermentation, a large portion 
of carbonic acid is disengaged. This in seeking to escape be- 
comes fixed in the cellular tissue of the gluten, which being 
tenacious and elastic extends itself, forming a series of mem- 
branous partitions filled with gas, and thus swelling out the 
mass. When exposed to heat, as in baking, the gas expands 
still more, and the baked loaf becomes specifically much lighter 
than before. 

843. It is very necessary in making bread to observe ; 1st. That the 
yeast should be mixed thoroughly with the dough ; otherwise the bread will 
be heavy in certain portions. 2d. The dough will rise light in proportion 
to the quantity of gluten, contained in the flour ; for this reason wheat flour 
makes better bread than any other. 3d. Substances which contain no gluten 
cannot be raised with yeast. Thus the flour of Indian corn, cannot by itself 
make light bread, but may be advantageously mixed, in certain proportions 
with wheat or rye ; and potatoes though they are nutritious on account of 
the farina which they contain, can never be used for bread, except with the 
flour of the glutinous grains. When bread has been suffered to sour, or 
pass through the acetous fermentation, the acetous acid which is generated 
may be neutralized by a solution of pearlash, or some other carbonated al- 
kali ; in this case, the further disengagement of carbonic acid gas, by the 
tinion of its base with acetic acid will render the bread still lighter, though 
if the alkali is too freely used, it will acquire an alkaline taste, and a yellow- 
ish color. 

844. Saccharine fermentation produces sugar in bodies where 
it did not previously exist. It accompanies the germination of 
many buds, is produced in heating starch with sulphuric acid, 
and in the action of yeast, or gluten upon farina. When starch, 
which has been cpagulated by boiling water, is kept moist, 
during some time, a spontaneous change takes place, and sugar 
is produced. The germination of the buds of barley, in the 
malting process is an example of the saccharine fermentation. 

Vinous or Jllcokolic Fermentation. 

845. Fermentation takes place when sugar, or farina, the 
latter being readily changed to sugar, together with water, and 
a small portion of yeast, is exposed to a temperature from 60° 
to SO F. The liquor soon begins to exhibit marks of action ; 
bubbles of carbonic acid, attracting around them small portions 
of the yeast, form a froth on the surface ; the liquor, after a 
time, deposits the interposed substances, which disturbed it, 
and becomes clear. The sugar having disappeared, it is proba- 

843. Considerations important in respect to the making of bread. 

844. What is saccharine fermentation, and when does it take place ? 

845. Production of the vinous fermentation. Phenomena attending this 
fermentation. Experiment to illustrate the process of vinous fermentation. 
Change of sugar to alcohol. 



FERMENTATION. 321 

ble that it has been converted into alcohol and carbonic acid ; 
especially as the weight of the two latter is found to be about 
equal to the weight of the sugar. 

This process may be examined, by way of experiment, by placing about 
five parts of sugar, with twenty parts of water, and a very little yeast in 
a glass flask with a bent tube, the extremity of which opens under an in- 
verted jar, full of water or mercury, and exposing the whole to the proper 
temperature. The carbonic acid gas which is disengaged may thus be col- 
lected, and its weight, together with that of the alcohol which is now form- 
ed in the flask, may be readily ascertained. The quantity of yeast decom- 
posed is so small as not to be brought into the account ; the only part the 
yeast performs is that of exciting the fermentation ; the agency of atmos- 
pheric air is of no importance, as the operation proceeds equally well with- 
out it. 

According to Gay Lussac sugar may be transformed into alcohol, by taking 
from the former 1 volume of oxygen gas and 3 volume of the vapor of car- 
bon, constituing, by their union, one volume of carbonic acid gas. 

846. Many vegetable juices containing sugar, acids, mucilage 
and starch, undergo the vinous fermentation without yeast, 
owing to the presence of gluten, which seems, in many respects, 
analogous to it. Cider is thus obtained by the fermentation of 
the juice of the apple, wine from that of the grape, currant, 
gooseberry, &c. 

In the malting of barley, the grain, after being soaked, is spread upon a 
floor. When the fermentation begins, and the seed germinates, the process 
is interrupted by heat, and the barley remains in a saccharine state ; it Is 
now called malt. When malt is fermented with an infusion of hops, the 
liquid is called beer, ale, or porter, in all of which, alcohol is produced 
during the fermentation. Ale and beer are more liable to sour than wine, 
on account of the mufcilage and other principles which the former derive 
from malt. Alcohol may be obtained by distilling both the liquors produced 
by the vinous fermentation of saccharine fruits, and those which result from 
the fermented decoction of hops and malt. 

Acetous Fermentation. 

847. The vinous fermentation readily passes to the acetous, 
or that in which acetic acid is generated. The acid appears to 
result from a change in the constituent principles of the 
alcohol. That this change takes place, seems evident from the 
disappearance of the alcohol, and the simultaneous production 
of acetic acid in an equal proportion to the alcohol which had 
previously existed. Pure alcohol, mixed with yeast and exposed 
to a warm temperature, will undergo the acetous fermentation. 
The nature of the chemical action which thus changes alcohol 

846. Vinous fermentation produced by gluten. Malt, &c. 

847. Cause of the change from the vinous to the acetous fermentation. 
In what case pure alcohol may be made to undergo the acetous ferments 
tion. Distinction between the formation of acetic acid, and the acetous 
fermentation. 



322 PUTREFACTIVE FERMENTATION. 

into acetic acid is yet considered doubtful. It is necessary to 
distinguish between the mere formation of acetic acid, and the 
acetous fermentation. Most vegetable substances yield acetic 
acid when they undergo spontaneous decomposition. Mucil- 
aginous substances, even when excluded from the air, gradually 
become sour. But these processes appear essentially different 
from the proper acetous fermentation, when there is a visible 
movement in the liquid, with absorption of oxygen, and disen- 
gagement of carbonic acid. 

848. The acetous fermentation is attended by the following circumstances. 
When a vinous liquor is exposed to the atmosphere, at a certain tempera- 
ture, it yields a portion of its carbon to the oxygen of the air, from whence 
results carbonic acid gas, and a slight disengagement of caloric ; the liquid 
becomes turbid owing to the fox-mation of a filamentous matter, which, after 
much agitation, subsides in a jelly-like mass ; the alcohol is decomposed, 
becomes transparent, and is found changed to vinegar or acetic acid. The 
alcohol has been supposed to pass to the state of acetic acid, by yielding a 
portion of its hydrogen and carbon to the oxygen of the air,forming carbonic 
acid and water, and leaving ils remaining carbon, hydrogen and oxygen in 
the exact proportion for forming acetic acid. But according to the experi- 
ments of De Saussure, the volume of carbonic acid gas formed, is such as to 
show that all the oxygen absorbed from the air unites with the carbon of the 
alcohol, while the hydrogen must be disposed of in some other way than by 
combining with oxygen to form water, as is supposed upon the former theory. 

Putrefactive Fermentation. 

849. While organized beings possess life, the elements of 
which they are composed, remain combined according to the 
laws of the vital principle, which are often xontrary to those of 
affinity ; but when life is extinct, the laws of affinity prevail, 
and former combinations are broken up in the effort of the ele- 
ments to unite according to their chemical attractions. This 
movement of the particles of bodies is called putrefaction, or the 
putrid fermentation. It is more rapid in animals than in vegeta- 
bles ; and more rapid in vegetable substances, in proportion as 
their constitution resembles that of animal matter. A damp 
and stagnant air, and warm temperature, hasten the progress 
of this fermentation. When vegetables deprived of their living 
principle, are thus situated, they become converted into a black 
matter, called mould, disengaging at the same time a little oil, 
acetic acid, water, nitrogen, carburetted hydrogen, and carbonic 
acid. Animal matter under the same circumstances besides 
most of these products, gives ammonia, some nitric acid, and 
hydro-cyanic acid. All the gases which are disengaged carry 
with them a little decomposed animal matter, which gives them 

848. Circumstances which attend the acetous fermentation. 

849. Change which ensues in organic beings when life ceases, &c. Phe- 
nomena of the putrefactive fermentation. Products of this fermentation. 
Miasma of marshes, &c. 



ANIMAL CHEMISTRY 323 

a very offensive odor. The noxious miasma of marshes are sup- 
posed to be a gaseous principle, arising from the putrefactions 
of vegetable matter, but they have never been obtained in an in- 
sulated state, and it is not even known that they are a distinct 
principle of matter. 

850. The dark mould arising from putrefactive fermentation 
enriches soils, and fits them for the production, and nourishment 
of new plants. Thus, in the vegetable kingdom, we everywhere 
behold decay followed by renewed life. Why then should man 
fear to commit his organic frame to the dissolution of the sepul- 
chre, and the watchful eye of that Omniscient Power to whom 
every atom is known, and who can as easily re-assemble the 
dispersed elements, as he could at first have made man of the 
dust of the earth % And why should infidel man speculate 
upon the ability of the Almighty to raise the dead, because the 
atoms which composed these bodies, have successively held a 
place in other material forms 1 Having seen the powers which 
chemistry developes, shall we dare restrict the power of The 
Great Chemist of the Universe, to preserve amid the " wreck 
of matter" one minute atom, one little germ which may constitute 
our personal identity, and to form from this, that " celestial 
body" which is to be fashioned like unto His glorious body, im- 
mortal and incorruptible !"* 



CHAPTER XXXVI. 

ANIMAL CHEMISTRY, OR ANIMAL ORGANIC BODIES. 

851. Animals, like vegetables, are composed of different parts ; 
these parts, of different animal substances ; and these substances, 
of different proximate principles. The object of animal chem- 
istry, is to examine into the nature of those proximate principles, 
and their associations in the various solids and liquids of animals. 

We do not find in the analysis of the proximate, animal prin- 
ciples, any new ultimate elements. These proximate principles 
differ from the vegetable principles, in containing more nitrogen, 
in a stronger tendency towards putrefactive fermentation, and 
in giving off offensive odors during this process. 

* For an account of the chemical phenomena attending the germination, 
growth, respiration, &c. of plants, the student is referred to the author's 
" Familiar Lectures on Botany," where these subjects are discussed at large. 

850. Reflections on the new life which results from putrefactive fermen- 
tation. 

851. Composition of animals. The object of animal chemistry. Differ- 
ence between the proximate animal principles and the vegetable principles. 



324? ANIMAL CHEMISTRY. 

852. By destructive distillation, or exposing animal substances 
to heat in close vessels, we obtain their ultimate elements. 
These, in some cases, as in animal oil, are the same as we obtain 
in the destructive distillation of vegetable matter ; but, in the 
former, nitrogen in greater quantity is generally obtained and 
sometimes a little phosphorus and sulphur. The ultimate 
elements of animal matter may be, in general terms, stated as 
nitrogen, hydrogen, carbon and oxygen. 

853. Animal substances are formed by the various operations 
of a living principle, as respiration, circulation, nutrition, se- 
cretion, &c. The proximate animal principles are less numerous 
than the vegetable. They may be divided into, 1st. Neutral 
principles, or those that are neither fat nor acid ; 2d. minimal 
acids ; 3d. Animal substances which are fat, without being acid ; 
and kth. Saline and earthy matters. 

854. The first division includes fibrin, albumen, gelatine, 
&c. These principles contain a large proportion of carbon : 
hydrogen is in proportion to take up all their oxygen to form 
water, and all their nitrogen to form ammonia. But in destruc- 
tive distillation, these elements are obtained under a variety of 
combinations; as some water, carbonic gas, carbonic oxide, 
carbonate and hydro-cyanate of ammonia, a thick, black and 
foetid oil, carburetted hydrogen, nitrogen, and the carbonaceous 
matter which remains in the retort. This animal carbon is 
more effectual as a clarifying agent than vegetable charcoal, 
and is less easily consumed, on account of its containing some 
phosphates and perhaps oxides of iron and manganese. 

855. Fibrin is that part of animal muscle which gives the 
power of motion, by alternate contraction and relaxation. It 
constitutes the greater part of muscular flesh, and appears to 
be that substance immediately acted upon by the nervous matter, 
which is supposed to communicate directly with the sensorium 
or brain, from whence emanate the impulses which produce 
voluntary motion. Fibrin constitutes a large proportion of the 
blood, and exists in other animal fluids. 

856. Pure fibrin is without taste or odor, of a yellowish color, and semi- 
transparent. Fibrin may be obtained by beating blood, recently obtained 
from the veins, with a bundle of twigs ; it attaches itself to the sticks un- 
der the form of long, reddish filaments, which become colorless by repeated 
washing with cold water. According to Gay Lussac and Thenard it is 

852. Destructive distillation. Ultimate elements of animal matter. 

853. Animal substances cannot be recomposed. Four classes of proxi- 
mate animal principles. 

854. Substances included in the first class, &c. 

855. What is fibrin ? 

856. Properties of fibrin, &c. How obtained ? Constituent elements of 
fibrin, &c. Proteine. 



ANIMAL ALBUMEN. 325 

composed of 53.360 parts of Carbon ; 19.934 parts of Nitrogen; 19.685 
parts of Oxygen ; 7.021 parts of Hydrogen. — 100.000. These proportions 
when reduced to equivalents, have been thus stated by Dr. Hare. Carbon 
18 equiv. — 108. Nitrogen 3 equiv. =42. Oxygen 5 equiv.=40. Hydrogen 
14 equiv. = 14. — Equiv. of fibrin=104. 

Mulder, a German chemist, obtained by the decomposition of fibrin a sub- 
stance which he called proteine, a name derived from the Greek, signifying 
to take the first rank. This is considered by Leibig as the chief constituent 
of the blood, and of fibrin and other animal tissues which are formed from 
the blood. The formula of relative properties given for proteine by Leibig 
is, Car. 48, Hyd. 36, Nit. 6, Ox. 14. 

857. JJnimal albumen. The purest form in which it is known to 
exist, is in the white of eggs* though here, it is united with 
water, soda, and sulphur. The free soda contained in the al- 
bumen of the egg is sufficient to green, slightly, blue vegetable 
infusions. Albumen exists in most of the animal solids and 
fluids. It is the germ of all animal matter; the starting point 
of all tissues, as cartilage, bones, hair, shell &c ; and it exists 
in the skin, membranes, and muscles. In a liquid state, it 
exists in chyle, and blood, in the coagulable part of milk or 
that which becomes cheese, and forms a part of various other 
animal fluids. 

It is heavier than water, and perfectly soluble. Its peculiar 
property is that of coagulating by heat, alcohol, and strong 
acids. 

858. It is the property of coagulating, which renders albumen useful in 
clarifying liquors. Thus blood, which contains a large portion of albumen, 
is used to clarify the syrup, in the manufacture of sugar. And the use of 
the white of eggs to clarify liquor fur jellies and preserves, is common in 
culinary operations. In these cases, the albumen, mixed in a very small 
proportion with the liquors, coagulates by heat and entangles in its sub- 
stance all the sediment, or undissolved particles, which it carries to the 
surface of the liquid where they form a scum which may easily be removed. 
When albumen is used to clarify wine and cider, it is coagulated, by the 
vegetable acids and by alcohol, without heat. 

The constituent elements of albumen and fibrin have been found by Lei- 
big and others to be the same, and in the same proportions. With potassa, 
and soda, albumen forms a soap-like compound from which it is precipitated 
by acids in a coagulated state. Phosphoric acid does not precipitate albu- 
men, but it is precipitated by pyro-phosphoric acid, also by metallic salts, 
tannin, and corrosive sublimate ; for the latter it is a very delicate test, 

* The word albumen was first applied only to distinguish the white of the 

e £gs. 

857. Purest form of albumen. Its extensive existence in animals, and 
animal matter. Peculiar property of albumen. 

858. Use of albumen in clarifying liquors, &c. Albumen compared with 
fibrin. Substances which precipitate albumen. Change which takes place 
in an egg when placed in boiling water, &c. Opinions as to the cause of 
the coagulating of albumen, &c. Putrefactive tendency of albumen in a 
fluid state, &c. Sulphur in albumen. Test of the presence of albumen in 
animal fluids. An antidote to metallic poisons. 

28 



326 ANIMAL ALBUMEN. 

causing a visible white precipitate in a fluid containing a very small pro- 
portion of that poison. When coagulated by heat albumen becomes inso- 
luble in water. If an egg taken from its shell, be put into boiling water, 
the white does not dissolve or mix with the water, because it almost in- 
stantly, begins to coagulate. In about three minutes it is boiled sufficiently 
for the table. Eggs may be thus boiled more delicately for the sick than 
with the shells on ; in the latter case the outer portion of the white may be- 
come too much hardened, while the inner part is under done. Fresh eggs 
being full, do not cook as soon in the shell, as those twenty or thirty days 
old, which have a small vacuum at one end, owing to the escape of mois- 
ture through the pores of the shell. In six or seven minutes boiling, the 
albumen of the egg becomes solidified, and continued boiling would but 
serve to increase its hardness up to a certain point. From the insoluble 
nature of albumen, after being hardened by heat, we may infer that hard- 
boiled eggs, are indigestible food. Cheese, which is chiefly albumen hard- 
ened by pressure and desiccation, is of the same nature, and should not be 
eaten in large quantities. 

There are different views as to the cause of the coagulation of albumen. 
Fourcroy attributed it to oxygenation. " But, says Thenard, " albumen 
coagulates as readily without as with access of air, and in alcohol as well 
as by heat, we must therefore refer this change to cohesion." The affinity 
between water and albumen appears slight, and is diminished by heat, until 
quite destroyed, the cohesive principle prevails, and albumen becomes a 
solid mass. The union of the water of fluid albumen with alcohol, would 
produce heat, and this would still further promote the decomposition of the 
albumen. The same cause operates when the strong acids are added to 
albumen : viz, the attraction of those acids for water, and the increase of 
temperature which takes place as these two fluids unite. 

Fluid albumen readily putrefies ; this may be observed in the case of an 
egg taken from the shell, when suffered to stand a few days, exposed to the 
air at a warm temperature. Even eggs protected by the shell require to 
be kept in salt, lime, or powdered charcoal, in order to preserve them for 
any great length of time. Coagulated albumen putrefies with difficulty; it 
therefore follows that hard-boiled eggs may be preserved much longer than 
eggs which have not been boiled. 

Albumen contains some sulphur; thus when blood is suffered to evapo- 
rate in a silver vessel, the vessel becomes tarnished by sulphuret of silver ; 
and the same may be observed of silver spoons with which eggs have been 
eaten. Putrid albumen also gives off' the odor of sulphuretted hydrogen. 

Galvanism furnishes an excellent test of the presence of albu- 
men in animal fluids. When liquid albumen is exposed to the 
galvanic circuit, pure soda appears in the negative cup, and the 
albumen coagulates in the positive. This effect has been at- 
tributed to the decomposition of muriate of soda j the muriatic 
acid being thus left free, coagulates the albumen. On account 
of the insoluble precipitate which albumen forms with metallic 
salts and chlorides, by uniting with their acids, it is recommen- 
ded as an antidote to poisons of this nature, especially corrosive 
sublimate and mercurial salts. 

859. Gelatine or Animal Jelly constitutes the greater part of 

859. What parts of animals contain gelatine ? How obtained. Glue. 
Paper maker's size. Isinglass. Calve's foot jelly, &c. Portable soup, &c. 
Gelatine with alcohol, sulphuric acid, &c. 



ANIMAL ALBUMEN. 327 

the skin of animals ; it is also contained in membranes, muscles, 
tendons, ligaments and cartilages, and even in bones and horns. 

It may be obtained by boiling these substances in water. The gelatine 
dissolves, forming a transparent solution, which, when evaporated to a 
certain degree and cooled, gelatinizes or forms a semi-transparent, tremulous 
solid, as is seen in the jelly made by boiling calves' feet ; this is a hydrate, 
containing a large portion of water, in which it readily melts wilh a slight 
degree of heat. By continued evaporation it hardens, loses its transparency, 
and acquires a vitreous appearance. Glue is gelatine thus prepared, and is 
procured by boiling the skins and hoofs of animals. The size used by paper- 
makers is glue much diluted ; it is used to give the paper a smooth surface, 
and prevent ink from spreading. Paper without sizing is sometimes called 
bibulous or blotting paper, because it readily absorbs moisture. 

Isinglass* which is used for blanc-monge and jellies, is gelatine obtained 
from the sounds of fishes. It is usually pure and white, and being evapora- 
ted to a very dry state, is a concentrated gelatine, requiring but a small por- 
tion, dissolved in boiling water, to form a gelatinous mass when cool. 
Calves' -foot-jelly is made by boiling the feet of calves, straining and evapo- 
rating the liquor, and adding sugar, wine, lemon and spices, to give it an 
agreeable flavor. Hartshorn shavings, or small shavings of the horns of the 
hart, yield gelatine, which is considered as peculiarly nutritive for the sick. 
When gelatine is distilled, hydrogen and nitrogen unite and form ammonia ; 
which was formerly considered as a peculiar product of the hartshorn, and 
received the name by which it is generally known. 

Portable soup may be made by boiling meat, or even bones for a sufficient 
length of time, straining and evaporating the liquor, and then drying it in 
thin cakes, by a slow, gentle heat. These cakes will keep for years, and 
form a very concentrated nourishment. As there is a great deal of gelatine 
in bones, it should be made an object in domestic economy to preserve the 
bones of roast meat for soup. There is a richness of flavor in soup prepared 
from such bones, that cannot be given to that made from joints of meat that 
have not been thus cooked. Soup is less used in domestic economy than it 
should be, considering that, on account of the gelatine it contains, it is one 
of the most nutritious kinds of food, and that those joints of meat which are 
the least expensive! furnish the greatest proportion of gelatine. By means 
of the strong heat which may be applied in Papin's digester, bones are readily 
dissolved, and their nutritious qualities thus extracted. 

Gelatine is insoluble in alcohol, but dissolves in most of the diluted acids. 
Sulphuric acid converts it into a kind of sugar. Common vinegar, with a 
gentle heat, dissolves isinglass, forming with it a cement for glass and china. 
Gelatine does not, like fibrin and albumen, form with alkalies soapy com- 
pounds which may be precipitated by acids ; but it dissolves with hot caustic 
alkali, and forms a brownish viscid substance, without those properties. 
Gelatine differs from albumen in not readily precipitating metallic solutions. 
860. Gelatine is remarkable for its property of combining with 
tannin ; by this means, the skins of animals are hardened, and 
converted into leather. The skins being freed from hair, fat, 

* Fish glue or ichthyocol. 

t There are what the butchers call hock-bones, or the lower joints of the 
. legs of neat cattle which, being abundant in cartilage and tendons, are rich 
in gelatine. 

860. Action of gelatine with tannin. Skins converted into leather. Ele- 
ments of gelatine compared with those of fibrin and albumen. 



323 ANIMAL ACIDS. 

&c. by various processes are little else than gelatine, bound to- 
gether by fibrous matter. Thus prepared, they are laid in vats, 
or solutions of tannin. The latter, gradually leaving the water, 
forms with the gelatine a firm and insoluble union. By means 
of various improvements, which have been the fruits of chemical 
discovery, the process for tanning leather has been shortened, 
from two or three years, to a few months, or even weeks. 
Gelatine contains less carbon and nitrogen than either fibrin or 
albumen, and more oxygen and hydrogen. 

Osmazome, 

861. Was found by Thenard in the muscular flesh of animals, and in 
mushrooms. It is obtained by dissolving small pieces of animal muscle in 
cold water; on boiling the liquor, the albumen rises to the surface, from 
whence it is removed ; the remaining liquor is filtered, evaporated to a 
syrup,* and heated with strong alcohol, which dissolves the osmazome, and 
precipitates muriate of soda and potassa. On evaporating the alcoholic 
solution, pure osmazome is obtained. It is of a yellowish brownish color, 
with an agreeable taste and odor. It is to this substance, according to The- 
nard, that soup owes its flavor, 1 part of osmazome being combined with 7 
parts of gelatine. 

Sugar of Milk. 

862. By evaporating whey the saccharine principle of milk is obtained. 
It is insoluble in strong alcohol, which gives a test for the sugar of milk, 
when used, as it sometimes is, for adulterating the sugar of the cane. It is 
less sweet than vegetable sugar, and does not suffer the vinous fermenta- 
tion with wafer and yeast. According to analysis of this animal sugar, it 
contains no nitrogen, but carbon, oxygen, and hydrogen in very nearly the 
proportions of other sugar. 

Second Class of minimal Substances, or Animal Acids. 

863. By the term animal acids we mean such acids only as 
are the sole result of animal organization, and found only in the 
animal kingdom. 

We shall give but few examples of these acids, as their study belongs ra- 
ther to medical, than chemical science. 

Lactic acid was discovered by Scheele in sour whey. According to Ber- 
zelius, it exists in blood. It is a thick, uncrystalizable liquid, soluble in 
water, and alcohol, and combines with bases, forming soluble salts. But 
the existence of this acid is regarded as uncertain. It has been suggested 
by Berzelius that it may be aeetic acid, united to animal matter ; or perhaps 
identical with zumic acid. Formic acid from formica, an ant, is extracted 
from ants ; its specific gravity is greater than that of acetic acid, which it 
resemb les in its properties. Saccholactic or mucic acid, is obtained by heat- 

861. Mode of obtaining osmazome. Properties, Sec. 

862. How is sugar of milk obtained ? Alcohol a test. Sugar of milk com- 
pared with vegetable sugar. 

863. What is meant by the term animal acids. Lactic acid. Formic 
acid. Saccholactic acid. Caseic acid. Butyric, capric, and caproic acids. 
Sebacic acid. Stearic acid, &c. Choleic and cerebric acids. 






ANIMAL OILS. 329 

ing the su^ar of milk with nitric acid ; hut as it is now known to exist in 
gums, and many other vegetable substances, it can no longer be regarded, 
exclusively, as an animal acid. Caseic ucid gives to old cheese its peculiar 
odor ; it is of a yellow color, with a taste like cheese ; nitric acid converts 
it to oxalic acid. It gives ammonia by distillation, and is precipitated white, 
by a secretion of nut-galls. It forms with ammonia an uncrystalizable salt. 
Butyric acid was discovered by Chevreul in butter. It inflames on the 
near approach of a burning body, does not solidify at 15° below zero. 
Capric acid has been obtained from butter made of cow's milk ; and caproic 
acid from butter made of goat's milk. Sebacic acid was discovered by 
Thenard in the recipient after the distillation of hog's lard. It contains no 
nitrogen. It combines with alkalies, forming salts called sebates. Stearic, 
Margaric, Okie, and some other acids discovered by Chevreul in a series of 
experiments on animal fat substances will be noticed in treating of that 
class of bodies. Choleic acid is the chief constituent of bile, in which it 
exists with soda, forming a saponaceous compound. Cerebric acid, combined 
with soda,forms the chief constituent of the fat found in the brain. 

Third Class of minimal Substances / minimal Oils, or Fat 
Substances. 

864. Bodies of this class melt at a low temperature, are in- 
sipid, very inflammable, insoluble in water, and give by distilla- 
tion foetid oil, and a carbonaceous residuum. When their 
vapor is made to pass through a heated tube, carburetted hy- 
drogen is disengaged. They contain no nitrogen, and but a 
small proportion of oxygen, and form soap with alkalies. These 
bodies are known under various names, as fat, oil, suet, lard, 
tallow and butter. They vary amongst themselves in hardness, 
and some other properties. When an animal substance is boil- 
ed, the fat, being specifically lighter than water, floats, and may 
easily be removed. In some cases, as in what is called by 
housekeepers the trying of lard, the fat being incorporated with 
a fibrous texture, requires to be for some hours exposed to a 
moderate heat, and then strained, in order to separate it from 
the fibrin. 

865. Train or fish Oil, is obtained from the blubber of the whale. It is 
the common lamp oil, and is used in making oil gas. It is often so impure, 
as to give an offensive odor in burning. On account of the quantity of car- 
bonaceous matter which settles upon the wick in burning impure oil, it is 
unsuitable for arsrand or astral lamps. The wick becoming encrusted with 
animal charcoal, its little capillary tubes which pumped up the oil and thus 
feil the flame, are prevented from performing their olfice, and the lamp goes 
out. This mortification to housewives, might be spared, if care were taken 
to procure good winter strained oil, to keep the lamps clean, and to tip the 
wick occasionally with spirits of turpentine, in order to render it more in- 
flammable. Train oil is composed of 

864. General properties of the third class of animal substances. 

865. Train oil, its use, properties, &.c. Why unsuitable for astral lamps, 
&c. Composition of train oil. 

28* 



330 STEARIN AND ELAIN. 

Carbon, 13 Equiv.=72 per cent. 68.87 

Oxvgen, 2 " =16 " 16.10 

Hydrogen. 17 " =17 " 15.03 

Chem. Equiv. " 105 100.00 

866. Spermaceti is obtained from the head of the sperm whale. It is found 
in an oily matter contained within a bony cavity of the head, and not in the 
brain of the whale. It is put into bags, and subjected to pressure : the part 
which is fluid and can be strained out at a low temperature, is called wintei 
strained oil ; this will resist the ordinary cold of winter without congealing, 
and burns in lamps without incrusting the wick. After the oil has been 
pressed out of the spermaceti, it is melted, strained, and washed with a 
weak solution of potassa; this is the spermaceti of commerce. It is softer 
and more brittle than white wax, and chiefly used for candles. It dissolves 
with boiling alcohol, and on cooling is deposited in the form of brilliant 
scales, called by Chevreul, cetine. This is pure spermaceti. Cetine forms 
a soap with potassa, which, when decomposed by an acid, gives rise to a 
substance, called ethal, from a combination of the first syllables of ether and 
alcohol, to both of which it has some resemblance. 

867. Stearin and Elain. It was discovered by Chevreul that 
animal fat, and the fixed vegetable oils are not pure proximate 
principles, but consist of one substance which is hard at common 
temperatures, and another which is fluid. The former he called 
stearin from the Greek stear, suet ; the latter elain from elaion, 
oil. Beef-suet, lard, and butter maintain their solidity at com- 
mon temperatures, because they contain a greater proportion of 
stearin than of elain ; while oil, in which elain exists more 
abundantly, is fluid except at very low temperatures. 

These principles were obtained by Chevreul by dissolving pork-fat in 
boiling alcohol ; after standing some time, the liquor was decanted, and to 
the undissolved fat was then added a new portion of boiling alcohol. The 
process was repeated until the whole was dissolved. Each portion of alco- 
hol, on cooling, deposited stearin in white needle shaped crystals, while 
elain, which remained in solution, was obtained pure by evaporating the 
alcohol. Elain resembles olive oil in appearance ; it is considered valuable 
for oiling the wheels of watches, and other delicate machinery, as it remains 
fluid at a very low temperature, and does not unite with the oxygen of the 
air to become an acid. 

All fat substances contain stearin and elain, and are firm or soft, in pro- 
portion as one or the other prevails. Thus hog's-lard contains stearin 38 
parts, and elain 62 ; while olive oil contains stearin 28 parts, and elain 72. 
Their ultimate elements, are 

Stearin. Elain. 

Carbon 79.030 78.776 

Hydrogen 11.422 11.770 

Oxygen 9.548 9.454 

868. When fat substances are heated with an alkali, a remark- 
able change appears to take place in the arrangement of the 

866. Spermaceti. Winter strained oil. Spermaceti of commerce. Cetine. 
Ethal. 

867. Discoveries of Chevreul with respect to animal fat, &c. Manner 
in which stearin and elain were obtained. Use made of elain in the arts. 
Proportions of stearin and elain. Ultimate elements of stearin and elain. 



ADIPOCIEE. 331 

proximate principles. Stearin and elain are decomposed, and 
their elements arrange themselves in several new compounds, 
ca\\ed-margaritic, stearic and oleic acids and glycerine. The 
process of forming soap cosists in the union of the acids with 
the alkalies employed, forming margarate, stearate and oleate of 
potassa or soda. 

According to Chevreul, to whom science is indebted for these 
discoveries, saponification is the change which fat substances 
undergo in the arrangement of their elements, by the action of the 
alkali. Those elements, having combined, in proportions to 
form acids, unite with the alkali which is presented to them, 
and form salts, which are soluble in water, and capable of com- 
bining with it in all proportions. Thus soap is not, as was 
formerly considered, a direct combination of oil and alkali, but 
a mixture of various salts resulting from the union of acids and 
alkali. The nature of the compounds formed, differ in different 
kinds of soap. That which is made with the fat of pork, beef, 
&c, contains more stearate than that which is made with 
human fat, the latter consisting chiefly of margarate and oleate. 

Soap is hard in proportion to the quantity of margarate or stearate it con- 
tains, and soft when the oleate prevails. Much also depends upon the 
nature of the alkaline base; as soda lends to render soap hard, and potassa 
soft. Thus the stearate of soda will form the hardest soap, and the oleate of 
potassa the softest. The hardness of soap is also increased by exposure to 
the air, or evaporation from any cause. 

869. Glycerine is the sweet principle of oils : it is formed by 
the action of metallic oxides, upon fat substances, or in other 
words, during saponification. It may be obtained in the form 
of sweet, uncrystalizable syrup. 

Adipocire (from adeps, fat, and cera, wax) is a white, pearly sub- 
stance resembling spermaceti, formed from human bodies when 
subjected to slow decomposition, under water, or in wet places. 

Fourcroy whose attention was first directed to the subject, regarded this 
matter as an ammoniacal soap with excess of fat.* Chevreul by a minute 
analysis has found that it consists of some ammonia, potassa and lime united 
with much margaritic acid, (to which it owes its peculiar whiteness,) and a 
little oleic acid. 

It may be obtained by keeping animal muscle, for some months 
in a running stream ; or, more rapidly, by digesting the muscle 
in nitric acid, and then exposing it to the action of water. 

* The phenomenon was first observed on opening the graves in the cem- 
etery of the Innocents at Paris in 1782. The superstitious regarded it as a 
miraculous testimony to the holy lives of the persons whose bodies were 
thus changed to a pearly white. 

868. Effect of alkalies upon fat substances. In what consists the process 
of forming soap, or saponification ? Cause of the hardness or softness of 
soap. 

869. Glycerine. Adipocire. 



332 GASTRIC JUICE. 

Fourth Class of Animal Substances ; or saline and earthy matters 
and the soft or solid parts of animals. 

870. All the humors, and many of the soft and solid parts of 
animals contain a certain quantity of saline and earthy matter. 
The phosphate of lime, muriate of soda and carbonate of soda 
are found to be most common. 

No law of animal existence is more admirable than that by 
which food is converted into blood. First the food dissolving 
in the stomach, becomes a pulpy matter, called chyme ; the lat- 
ter either passes into the intestines, or becomes a milky liquid 
called chyle. The chyle forms bloody and the blood is converted 
into the various liquid secretions and solid parts of the body. 

871. By secretion is understood a process, in which any par- 
ticular organ, by decomposing blood, forms a substance peculiar 
to that organ. It is thus that all animal fluids, except the 
chyle and blood are formed. Most of the fluids of secretion 
remain in the body, and then fulfil some peculiar office. 

872. The bile is a bitter, yellowish-green secretion, formed in 
the liver, from venous blood. By mixing with the chyme in the 
stomach, it acts an important part in converting it into chyle, and 
is also a necessary stimulus to the bowels. Human bile consists 
of choleic acid, a bitter resin, albumen, soda, some of the salts of 
soda, as the sulphate, phosphate and muriate, oxide of iron, and a 
large proportion, (about 90 per cent) of water. In diseased per- 
sons the proportion of resin is less, and that of albumen greater, 
than in those who are in health. A peculiar substance, called 
picromel,* has been discovered in human bile, in that of the ox 
and some other animals ; and it is supposed to exist in all. It is 
of consistence of turpentine, of a bitter taste, and without odor. 

873. Gastric juice is a secretion of the stomach, and the prin- 
cipal agent in digestion. It has a saline taste, and does not 
give either the acid or alkaline test with vegetable colors. 
Though apparently a mild, neutral liquid, it possesses a remark- 
able solvent power. It dissolves the food introduced into the 
stomach and changes it into the pulpy substance, chyme. Ex- 
periments made with the gastric juice taken from the stomach of 
an animal killed while fasting, have proved that this liquid is ca- 
pable of dissolving very insoluble substances ; — and it is known 
that after death, or in excessive fasting, the gastric juice turns its 
active energies upon, and seizes the coats of the stomach itself. 

* From the Greek picros, bitter, and mege, honey, so called from its pecu- 
liar taste. 

870. Saline and earthy matter found in animal substances. Change of 
food into blond. Chyme and chyle, &c. 

871. Secretion. 872. Bile. Picromel. 873. Gastric juice. 



BLOOD, 333 

874. Lymph is a colorless, saltish liquid, secreted in a set of 
vessels, called lymphatic, which have their origin in the ex- 
tremeties of the arteries, and extend over the surface of the 
cellular membrane. The liquid formed in them, lubricates the 
various cavities of the body, exists in blisters, and is secreted, 
in large quantities, in cases of dropsy. 

875. Synovia is a viscous fluid, secreted in the capsules of 
the joints, preserving their health and freedom of motion, and 
protecting them from injury. 

876. Saliva is an inodorous, tasteless fluid, secreted from the 
blood, by different glands around the mouth, and discharged 
into it through various ducts. Mixing with food it softens and 
dissolves it, and thus serves an important purpose in digesting. 
It lubricates the organs of speech, and thus enables them to 
perform their office with greater ease. In the analysis of this 
proximate principle, are found salts of various kinds, (chiefly 
hydrochlorate of potassa,) mucus, albumen, and a very large 
proportion of water. From the mucus existing in saliva, accor- 
ding to Thenard is deposited the tartar which incrusts the teeth. 

877. Blood is that part which, by its various transformations, 
gives rise to every part of the animal organism. Its color in the 
arteries is a lively red, and in the veins a deep purple. In res- 
piration, the dark venous blood enters the lungs, and being there 
exposed through a thin porous membrane to the action of the 
air, it absorbs oxygen inhaled by the lungs from the atmosphere, 
and becomes of a bright red color. 

Blood consists of a liquid through which are diffused small 
globules, which contain fibrin, the coloring matter and iron. 
The liquid portion consists of water holding in solution fibrin, 
albumen and salts. When blood is suffered to stand undisturbed 
it separates into a red coagulum called the clot, (crassamertum,) 
and a thin yellowish fluid called the serum. More than -fth. of 
the blood is water. 

878. The brain, skin, glands, tendons, muscles and bones ; — 
hair, wool, nails, teeth, shells, fyc , with various other substances 
constituting either the bodies of animals, or resulting from their 
organization, have been subjected to chemical analysis and 
though found to differ among themselves in their proximate prin- 
ciples, yet they consist of a small number of the ultimate ele- 
ments into which Chemistry has resolved all matter, whether 
of the inorganic or organic kingdoms. 

879. The late investigation of Dr. Leibig of Germany in Organic Chem- 
istry, have thrown much light upon some subjects, hitherto but little under- 

874. Lymph. 875. Synovia. 876. Saliva. 877. Blood. Color of arte- 
rial and venous blood. Parts of blood. 878. Brain, skin, &c. 879. Dr. 
Leibig's investigations in organic chemistry. 



334 VITAL ACTIVITY. 

stood. He has simplified the analysis of organic bodies, and established 
formula, and equations, upon principles of arithmeticafcalculation. He has 
attempted to ascertain and express in simple numbers those chemical forces, 
which, acting at insensible distances, produce in organized bodies the pecu- 
liar changes to which they are subject, and in a degree give laws to vitality. 
The higher phenomena of mental existence he does not profess to trace to 
their proximate, and still less to their ultimate causes ; these he justly refers 
to an immaterial agency, having nothing in common with the vital force. 

880. Dr. Leibig justly considers the efforts of philosophers to penetrate 
the relations of the soul to animal life ; but while we can never realize 
what life is, we may discover the laws of vitality, with the chemical or me- 
chanical causes which disturb, promote, or destroy it. We are also able in 
many cases to trace the influence of the spiritual nature within,in its effects 
upon the condition of the organic frame ; but the mysterious tenant of the 
building is invisible to our senses, and shrouded from our observation. 

881. Dr. Leibig's views of Organic Chemistry applied to physiology, may 
be briefly stated as follows : 

Vital force, or vitality, which is the spring of both vegetable and animal 
life, is a force which causes growth, and is capable of reproduction, or of 
supply of matter consumed. It is a force, which may be as in the seed of a 
plant, in a state of rest. 

882. The growth and developement of vegetables depend on the elimination 
of oxygen, which is separated from the other component parts of their nour- 
ishment. 

In animal life on the contrary, there is a continued absorption of oxygen 
from the air, and its combination with the animal body. While no part of 
an organized body can serve as food for vegetables until by the process of 
putrefaction and decay, it has assumed the form of inorganic matter; the 
animal organism requires for its support and developement highly organized 
atoms, and therefore the food of animals consists of parts of organism. 

883. The nervous system within the animal organism, is the source of 
the motion and force necessary to sustain the vital process. 

Assimilation, or the process of formation and growth, or in other words, 
the passage of matter from a state of motion, to that of rest, goes on in the 
same way in animals, and vegetables ; in both, it is carried on without con- 
sciousness. Though intellect adds to vitality a peculiar source of energy, 
or of disturbance, the soul has no more to do with the developement of the 
germ of animal life in the egg of a fowl, than in that of vegetable life in the 
seed of a plant. 

884. The first condition of animal life being the accumulation of nourish- 
ment, the second is absorption of oxygen from assimilation. As all vital 
activity arises from the mutual action of oxygen and the elements of food, 
in the processes of nutrition and reproduction, matter passes from the state 
of motion to that of rest, under the influence of the nervous system, this 
matter again enters into a stale of motion. The ultimate causes of these 
different conditions of the vital force, are chemical forces, the cause of a 
state of rest is a resistence determined by a. force of attraction, which acts 
between the smallest particles of mattter, or otherwise by chemical affinity. 

If in a closed galvanic circuit, a metal in contact with an acid undergoes 
certain changes, producing what is called a current of electricity, so, in the 
animal body, in consequence of changes undergone by matter previously con- 
stituting a part of the organism, certain phenomena of motion and activity 
are percieved, and to them we give the name of Life or Vitality. 

880. Laws of vitality. Chemical or mechanical causes. 881. Organic 
chemistry applied to physiology. 882. Growth of animal and vegetable life. 
883. Assimilation. 884. Vital activity. 



PHYSICAL MOTION. 335 

885. The great amount of oxygen introduced through the lungs, and 
through the pores of the skin into the animal system, is disposed of by com- 
bining with carbon, and hydrogen, which are furnished by supplies of food. 
It is considered that an adult person receives daily into his system 32£ oun- 
ces of oxygen, and that 13 and 9-10 ounces of carbon, unite with that to form 
carbonic acid gas, which escapes through the skin and lungs. 

Since no part of the oxygen taken into the system is given off in any other 
form but that of a compound of carbon or hydrogen, and since these are 
supplied by food, it follows that the amount of nourishment required for the 
support of the animal body, must be a direct ratio to the quantity of oxygen 
taken into the system. 

886. The consumption of oxygen in equal times may be expressed by the 
number of respiration ; it is clear that the quantity of nourishment required 
must vary with the force and number of respirations. The number of res- 
pirations is smaller in a state of rest than during exercise. The quantity of 
food necessary in both conditions must vary in the same ratio. An excess 
of food is incompatible with deficiency in respired oxygen, that is with suf- 
ficient excercise. The quantity of oxygen which an animal takes into 
the lungs, not only depends upon the number of respirations, but is affected 
by the temperature and density of the atmosphere. Air being expanded by 
heat, and contracted by cold, it follows that at different temperatures equal 
volumes of air must contain unequal weights of oxygen. 

In an equal number of respirations we consume more oxygen at the level 
of the sea, than on a mountain, where the air is less dense. It is a wise 
provision of Providence, that the articles of food in different climates, are 
very unequal in the proportion of carbon they contain. The fruits, on which 
the natives of southern countries usually subsist, do not contain more than 
12 per cent of carbon, while the bacon and train oil,used by the inhabitants 
of the polar regions, contain from 66 to 80 per cent of carbon. 

These facts being established mankind should seek to conform to the 
laws of their organic nature, and proportion their food to the climate in 
which they live, and the degree of exercise they take. 

*887. Animal heat is caused by the mutual action of the combustible hy- 
drogen and carbon of food, and oxygen or the great supporter of combus- 
tion ; these combining, are conveyed by the circulation of the blood to every 
part of the body. The carbon of the food which is converted into carbonic 
acid within the body must give out as much heat as if it had been burnt 
directly in the air, or in oxygen gas; but in the one case the combustion is 
rapid, in the other slow. 

The amount of heat liberated must increase or diminish with the quantity 
of oxygen introduced in equal times by respiration. Those animals which 
respire most frequently and consequently consume most oxygen, possess a 
higher temperature than others, which with a body of equal size to be heat- 
ed, take into the system less oxygen. Thus the temperature of a child is 
102°, that of an adult 99°. 

888. A deficiency of food, and a want of power to convert the food into 
a part of the organism, both equally cause a want of resistance. The flame 
goes out because the oil is consumed ; and it is the oxygen that has con- 
sumed it. 

889. There are various causes by which force or motion may be produc- 
ed. A bent spring, a current of air, the fall of water, fire applied to a 

885. Disposition of oxygen. Amount of oxygen introduced into the system. 

886. Consumption of oxygen. Number of respirations. Quantity of food. 
Situations which air contains the most oxygen. Properties of carbon in food. 

887. Cause of animal heat. Effect of increased respiration on animal heat. 

888. Result of deficiency of food. 889. Physical motion. Animal motion, 



336 RESPIRATION. 

boiler, the solution of metal in an acid, all these different causes of motion 
may be made to produce the same effect. But in the animal body we recog- 
nize as the ultimate cause of all force only one cause, the chemical action 
which the elements of the food, and the oxygen of the air mutually exercise 
on each other. The only known ultimate cause of vital force, either in ani- 
mals or plants is a chemical process. 

890. Theory of respiration. During the passage of the venous blood 
through the lungs, oxygen is absorbed from the atmosphere, and the blood 
changes its color. For every volume of oxygen absorbed, an equal vol- 
ume of carbonic acid is given out. The red globules of blood contain a com- 
pound of iron, which is found in no other constituent of the body. It appears 
that this is necessary to animal life from the great affinity of iron for oxy- 
gen, the globules readily become oxidised, they are now in a condition to 
combine with the carbonic acid which they meet with in travelling through 
the capillary vessels, and become the carbonate of protoxide of iron. 

It is in the capillary system that the functions of secretion, nutrition, ab- 
sorption, and calorification are performed. This seems to be the great 
work shop of the animal system, the globules having returned from the 
lungs towards the heart richly charged with oxygen, mingle with the arte- 
rial blood, and return to the lungs with a new supply of surplus carbonic 
acid which impedes the vital functions, and is emitted by the exhalation of 
the breath. 

Before taking a final leave of our subject, we would call tbe attention of 
the young to the effects which the study of the useful and noble science of 
Chemistry should have upon their own minds. Chemists are sometimes, 
most strangely led to confound the soul with matter; the laws of nature, 
with the providence of God. This unhappy result is owing either to a little- 
ness of mind, which cannot rise from effects beyond their secondary causes, 
or a pride of intellect which disdains to ascribe Supreme power to an un- 
known being. The phenomena of nature exhibit to the enlightened and 
humble Christian, an all wise and powerful Divinity who presides over, and 
governs all. The regular sequences of natural phenomena, so far from in- 
dicating the non-existence of a Deity, prove themselves to be the laws to 
which He has, wisely, subjected all material substances. The skeptic in- 
deed talks of the laws of nature; but how absurd to suppose the existence of 
laws, without a lawgiver ! 

We have shown, in a great variety of applications, the utility of Chemis- 
try considered in its economical relations ; — but, in taking leave of our sub- 
ject, we would refer to considerations of a higher and nobler nature. — We 
would bid adieu lo our science, not merely as to an agent subservient to 
material wants, but as a noble pursuit, in which, in addition to the pure and 
elevated enjoyment arising from the acquisition of knowledge, our souls have 
been raised to higher thoughts of God, and a better understanding of His 
operations. 

890. Theory of respiration. Change in the blood effected by the absorp- 
tion of oxygen. Process by which the changes in the blood is effected. 
Capillary system. 



THE END 



INDEX 



A. 



Acetates 

Acetate of copper 

lead.. 

morphia 

Acetous fermentation 

Acids, animal 

chemical properties of. 

definition of 

nomenclature of 

vegetable 

Acid, acetic 

aerial 

antimonious 

arsenie .. 

arsenious 

auric 



bengoic • 

boletic 

boracic 112 ; 

bromic * 

butyric 

camphoric 

capric ~- ..i^. . 

caproic 

carbazotic 

carbonic 97. 

caseic 

cerebric • 

chalkly 

chloric 

chloriodic 

chloro-cyanic 

chloro-carbonic 

chlorochromic • 

chlorous 

choleic • 

chromic 

chromous 

citric 

cobaltic 

cyanic 

cyanous 

dephlogisticated marine 

ellagic 

ferro-cyanic 

fluo-boric 

fluo-chromic 

fluoric 



238 
283 
295 
321 

328 
61 

71 
73 

2S7 
•2S7 
149 
201 
200 
199 
246 
291 
293 
172 
107 
327 
293 
329 
329 
292 
149 
329 
329 
149 
104 
HO 
170 
1G6 
204 
104 
329 
203 
203 
290 



Acid, fluo-silicic 113, 177 

formic 32S 

fulminic 167 

gallic 291 

hydriodic 128 

hydro-bromic 106, 127 

hydro-chloric 126 

hydro-citric 290 

hydro-cyanic 168, 234 

hydro-fluoric 110 

hydro-fluo- silicic 113 

hydro-selenic 194 

hydro-sulphuric. 192 

hydro-sulphurous. 192 

hydrous-sulphuric 190 

hydroxanthic 193 

hyporoxy-muriatic 104 

hypo-chlorous 104 

hypo-nitrous 137 

hypo- phosphoric 182 

hypo-sulphuric 188 

hypo-sulphurous 187 

indigotic 292 

iodic 109 

iodous 110 

kinic 294 

lactic 328 

lampic 304 

malic 290 

manganesic 207 

manganesious 207 

margaric 329 

marine 126 

meconic 29.5 

molybdic 204 

molybdous 204 

moroxylic 293 

mucic 292, 32S 

muriatic 126 

nitric 138 

nitro-hodro-chloric 127 

nitro-muriatic 127 

nitrous 137 

oleic 329 

oxalic 154, 28S 

oxy-muriatic 100 

pectic 292 

per chloric 105 

phosphoric 97, ISO 

phosphorous 181 



20 



338 



INDEX 



Acid, prussic 168, 

pyro-ligneous 

pyro-mucic • 

pyro-phosphoric 

pyro-tartaric 

rheumic 

saccholactic 292, 

sebacic 



seieutc 

selenious 

silicic 

silico-hydro-fluoric 

stannic 

stearic 

suberic 

succinic 

suipho-naphthalic 

sulphuric 

sulphurous 

tartaric 

tilanic 

tungstic 

ulrnic < 

vanadic 

zumic 

Adipocire 

Aeriform bodies, effect of caloric on. 

Affinity, simple 

elective, single 



disposing •• • 

quiescent and diveilent... 
by what causes modified. 

Air, atmospheric 

fixed ■ 

inflammable 

non-respirable 

Albumen, animal 

vegetable 

Alcoates 

Alcohol 

Algaroth, powder of. 

Alkali, volatile 

fixed ••• • •• 

Alkalies, chemical properties of. 

nature of 

vegetable 

Alloys of antimony 

copper 

gold 

lead 

mercury 

nickel 

silver 

sodium 

tin 

Almond oil 

Alum 

Alumina 

Aluminum 

oxide of. 

chloride of 

Amalgams 

Amber 

Amidine 

Ammonia 

cobaltate of 

muriate of. •• 

nitrate of ' 

sulphate of 

Ammoniuret of copper 

silver 



294 

288 

292 

181 

290 

294 

323 

329 
194 
194 
175 
177 
210 
329 
293 
293 
1C4 
183 
137 
289 
202 
206 
317 
206 
294 
331 
27 
77 
79 
80 
207 
81 
82 
130 
149 
114 
130 
323 
317 
302 
301 
200 
142 
218 
61 
211 
293 
201 
239 
247 
237 
243 
233 
245 
217 
211 
297 
265 
224 
224 
225 
226 
243 
300 
309 
140 
209 
142 
143 
2(i3 
267 
245 



Anatase 

Anhydrous alum 

Animal, acids 

albumen 

chemistry 

heat 

J e,1 y 

oils 

substances, analysis of 

Anions ." 

Annotta 

Antharcite 

Antimoniates 

Antimony 

oxides of 

alloys of 

chlorides of 

sulphuret of 

argentine flowers of 

Apparatus, distilling 

Aqua ammonia 

fortis 

regis 

Arbor Dianae 

Saturni 

Archil 

Argand lamp 

Argellite 

Argentine flowers of antimony 

Arrow root 

Arseniates, 200. 

Arsenic 

cromide of 

chloride of 

iodide of 

sulphuret of 

Arsenites 

Ashes 

Asparagin 

Assimilation 

Atmospheric air 

analysis of 

Atomic theory 

Atropia 

Attraction 

Azote 



B. 



Baldwin's phosphorus. 

Balsams 

Bark, Peruvian 

Barilla 

Barium. . • 

oxides of 

Baromcler 

Baryta, sulphate of. • . • 

Bass-orin 

May berry tallow 

Bell metal 

Benzoates 

Berillia 



Bile 

Bismuth 

oxide of 

chloride of • ■ 
nitrate of. . • 
flowers of. • • 

Bitartnte of potassa. 

Bitter principle 

Bittern 

Black dye 



202 
264 
328 
325 
323 
335 
326 
329 
324 

62 
314 
146 
201 
200 
201 
201 
200 
201 
201 

45 
141 
13S 
240 
24 5 

313 

27 

236 

301 

309 
273 
199 
200 
200 
200 
200 
273 
145 
317 
334 
130 
132 

90 
29G 

12 
130 



53 

300 
295 
275 
218 
2)9 
130 
263 
317 
300 
239 
291 
227 
332 
240 
240 
240 
240 
240 
'..90 
319 
, 278 
314 



INDEX 



339 



Black drop 295 

wad 207 

Black lead 231 

Blacking 102 

powder.- 103 

Blende 233 

Blood 99, 333 

Blowers. 158 

Blowpipe, compound 1 17 

Blue, Prussian 282 

celestial 267 

dyes 312 

vat 312 

Boiling point of liquids 41 

influence of pressure on 42 

Bolognian phosphurus 53 

Boracic acid 112, 172 

Borates 274 

Borax, glass of » 274 

Boron 170 

chloride of 173 

fluoride of 173 

Brass 239 

Brazil wood 313 

Bromates 272 

Bromic acid 107 

Bromine 105 

chloride of 107 

properties of 106 

Bronze 211 

Brucia 295 

Burgundy pitch 299 

c. 

Cadmium 235 

oxide of , 235 

sulphuret of 235 

Caffein 317 

Calamine 233 

Calcareous earth 220 

Calcium 220 

oxides of. 220 

chloride of 221 

Calcined magnesia 276 

Calions 62 

Calomel 242 

Caloric 13 

absorption of 30 

conduction of 24 

expansion by, of solids 14 

of liquids 17 

of aeriform bodies 20 

offluidity 34 

latent 32 

radiation and reflection of 28 

specific 34 

sources of .14 

Calorific rays 50 

Calorimeter, Lavoisier's 33 

Hare's 58 

Calcs, mercurial 241 

Calx 220 

Camphor 299 

Camphorates 299 

Cannon metal 239 

Canton's phosphorus. 53 

Caoutchouc 300 

Carbon. 144 

crystallized 146 

chloride of 166 

phosphuret of,.... ......... ... 185 



Carbon, properties of 147 

sulphuret of 19-2 

Carbonates 153, ^74 

of ammonia 156, 75 

Carbon ic acid . 97, 149 

oxide 154 

Carburetted hydrogen 158 

Carmine 313 

Cassius, precipitate of 247 

Cassava 309 

Castor oil 298 

Cathartic 317 

Caustic, lunar 269 

Celestial blue 267 

Cerin 301 

Cerium 235 

oxides of 235 

Cerite 235 

Ceruse 276 

Cetine 330 

Chalcolite, 206 

Chalk 276 

Chameleon, mineral 207 

Charcoal 145 

Cheese 3^6 

Chemical affinity 97 

classification 93 

combination, laws of 86 

equivalents. 88 

nomenclature. 70 

rays 50 

Chemistry, animal 323 

definition of 17 

object of 7 

organic 284 

vegetable 286 

Classification of chemicel substances ... 93 

Chlorates 270 

Chloric acid 104 

ether 163 

Chloride of boron 173 

bromine 107 

carbon 166 

cyanogen 170 

gold 102 

lime 103, 222 

lithicum 218 

magnesium 224 

nitrogen 143 

phosphorus 182 

silicon 177 

silver 103 

sodium 124,216 

sulphur 192 

Chlorine 100 

chemical character of 101 

testsof 103 

Chloriodic acid 109 

Chloro-carbonic acid 166 

Chlorophyle 318 

Chlorous acid. 104 

Chromium 203 

oxides of 203 

phosphuret of 204 

Chromates 273 

Chrome yellow 273 

Chyle 332 

Cinchonia 295 

Cinders, blue. 267 

Cinnabar 241 

Citrates 390 



340 



INDEX. 



Coal 145 

Cobalt 208 

oxides of 209 

Cochineal 313 

Codeia 296 

Coke 146 

Colocynthin 318 

Colorific rays 49 

Colors, substantive and adjective 312 

Coloring matter 311 

Colurnbates 202 

Columbium 201 

oxide of 202 

Combination, chemical • 1 IS 

Combustion of charcoal 148 

oxygen 96 

theories of 98 

Common sait 216 

Compound blowpipe 117 

Conductors of caloric 24 

Conia 296 

Copal 300 

Copper 233 

oxides of 239 

chlorides of. 239 

sulphurets of 239 

hydrates of. 240 

alloysof. 239 

pyrites of 239 

amminiuret of 267 

Copperas 265 

Cork 317 

Corrosive sublimate 242 

Coumarin 289 

Couronne des Tasses 57 

Creosote 300 

Cream of tartar 289 

Crocus 213 

Cruickshank's trough 67 

Cryophorus, Wollaston's 38 

Crystallization 84, 245 

water of. 122 

Crystals, primitive 256 

secondary 259 

Currents of air, how produced 27 

Curcuma paper 313 

Cyanogen 166 

chlorides of 170 

bromide of 170 

iodide of 170 

Cyanic acid 168 

Cyanous acid 167 

D. 

Daguerreotype 51 

Dahline 318 

Davy's safety lamp 160 

Decomposition of water 121 

Deflagration 59, 149 

Deoxidizing rays 51 

Dephlogisticated air 94 

marine acid 100 

Detonating silver 245 

Dew, formation of 32 

Diachylon plaster 297 

Diamond 146 

Differential thermometer 21 

Digester, Papin's 43, 327 

Distillation 45 

destructive 145,324 

Distilling apparatus 45 



| Dragon's blood 300 

Dyes 311 

black 314 

blue 312 

red 313 

yellow 313 

E. 

Earths 218 

Ebullition 40 

Elaine 330 

Elastic gum 300 

Elasticity, its effects on chemical affinity 84 

Elective affinity, single 79 

double SO 

Electricity 54 

animal 55 

Electrodos 62 

Electro-magnetic telegraph 68 

Electrolytes 62 

Electrograpby 69 

Electro-meguetism 64 

Amperu's theory of 67 

Electron 300 

Electro-negatives. 63, 93 

positives 63, 1 14 

Electrotype 63 

Emetia 296 

Emetic, tartar 201 

Empyreal air 94 

Empyreumatic oil 285 

Emulsion 297 

Epsom salts 264 

Equivalents, chemical 88 

table of 195 

Essences 293 

Essential oils 298 

Ethal 330 

Ether 303 

acetic 305 

auriferous 247 

chloric 163 

hydriodic 304 

hydro-chloric 304 

nitric 304 

oconanthic 305 

sulphuric 303 

Ethiop's mineral 243 

Euchlorine 164 

Eudiometer 132 

Eudiometry 132 

Evaporation 37, 84 

Exhilarating gas. • 134 

Expansion of aeriform bodies 20 

of solids 14 

of liquids 17 

exceptions to the law of 18 

Expansive force of freezing water 19 

of steam 47 

Extractive matter 313 

F. 

Fahrenheit's thermometer 23 

Fat of animals 329 

Fermentation, 319 

acetous 321 

alcoholic 320 

panary 319 

putrefactive 322 

saccharine 320 

vinous 320 



INDEX 



341 



Ferrocyanales "281 

Fibre, woody 310 

Fibrin 324 

Firedamp 15S 

Fixed air 149 

oils 296 

Flame 117, 159 

Flint glass 236 

Flints, liquor of 176 

Florentine glass 20 

Flour of sulphur 84 

Flowers of sulphur 186 

Fluate of lime Ill 

Fluo ric acid « Ill 

Fluoboric acid. • HI 

Fluoborates 112, 174 

Fluo-siiicic acid gas 113, 177 

Fluorides 279 

Fluorine HO 

Fluorspar 110, 222, 279 

Frigorific mixtures . 34 

table of 35 

Frost bearer 38 

Fulminating gold 247 

mercury 1C7 

silver 167, 245 

Fulminating powders 269 

platinum 250 

Fulminic acid 167 

Fuming liquor of Libavius 211 

Fungin 317 

Fusing point of metals 34 

Fustic" 313 

G. 

Galena 237 

Gallates 292 

Gall nuts 291 

Galvanic battery. 57 

modifications of. 58 

Galvani 54 

Galvanic circle 55 

Galvanism, history of. 54 

effects of. 59 

theories of 69 

Galvanometer 65 

Gases 46 

Gas, coal and oil. 164 

ammouiacal 141 

carbonic acid 149 

carburetted hydrogen 158 

chlorine 100 

fluo-silicic acid 1 13 

hydrogen 114 

nitrogen 123 

defiant 163 

oxygen 94 

sulphurous acid 187 

telluretted hydrogen. 205 

Gastric juice 332 

Gelatine 326 

Glass 176 

antimony 201 

etching on 101 

flint 263 

Glauber's salt 226 

Glauberite 263 

Gliadine 315 

Glucinum 227 

oxides of 227 

Glue 327 

29* 



Gluten 315 

Glycerine 331 

Gold 246 

alloys of 247 

carats of 24S 

chlorides of. 247 

fulminating 247 

oxides of 246 

stannates of. 247 

sulphuret of 247 

Goniometer 259 

reflective. 260 

Graphite . 231 

Gravity, effect on chemical union 85 

specific 74 

of gases 76 

of liquids 75 

of solids 74 

Gum 309 

elastic 300 

resins 300 

Gunpowder 269 

Gypsum 263 

H. 

Haloid bodies 124 

salts 282 

Hartshorne, spirits of 77, 275 

volatile salts of. 275 

shavings 327 

Haematite 230 

Hea , use of term 13 

animal 335 

Hematine 313 

Heavy spar 263 

Homberg's py rophorus 264 

sedative salt 172 

Honey 307 

Hydracids 74, 123 

Hydrate of baryta , 219 

oflime 221 

of potash 214 

of strontia 220 

Hydrates 123 

Hydriodates 278 

Hydriodic acid 128 

Hydro-bromk acid 106, 127 

Hydro-chlorates 277 

Hydro-chlorate oflime 222 

Hydro-chloric acid 126 

Hydro-chlorides 277 

Hydro-cyanates 281 

Hydro-ferro-cyauates 29 

Hydro-fluates 111,279 

Hydro-fluoric acid 110 

Hydrogen 114 

arseniuretted 200 

deutoxide of 123 

bi-carburet of 163 

carburetted. 158 

Hydrogen, phosphuretted 1S4 

properties of- 116 

seleniuretted 114 

sulphuretted 190 

telluretted 205 

Hydrometer 301 

Hydrostatic balance 75 

Hydro-sulphuric acid 192 

Hydro-sulphurous acid 192 

Hydro-sulphurets 279 

Hypo-chlorous acid 104 



342 



INDEX. 



Hypo-nitrous acid 137 

Hyosciamia 296 

I. 

Iceland spar 49 

Igneous fluid 13 

Imponderables 13 

Incandescent bodies 51 

Indigo 312 

Indigogene 312 

Indigotic acid 292 

Inflammable air 114 

Ink, sympathetic 209 

indelible 269 

Iodates 272 

Iodides 108 

Iodide of nitrogen 144 

of starch 108 

of sulphur ... 192 

Iodine 107 

bromide of 110 

chemical properties of. 110 

chloride of 110 

discovery of 107 

mode of obtaining 109 

natural history of. 10S 

Iodous acid 110 

Ions 62 

Iridium 251 

Iron 228 

carburets of 231 

cast 232 

chlorides of 230 

oxides of 229 

rust 230 

sulphuret of 231 

wrought 232 

Isinglass 327 

Isomeric bodies 157,180 

Ivory black 145 

J. 

Jargoon 226 

Jelly, animal 320 

vegetable 310 

K. 

Kelp 109,275 

Kinicacid 293 

L. 

Lac - 300 

Lakes 311 

Lamp, flameless 161 

safety 160 

spirit 301 

black 145 

Latanium 252 

Latent caloric 32 

Lead 235 

alloys of. 237 

chlorides of 237 

muriate of 237 

oxides of 236 

red 236 

sulphuret of 237 

Legumen 317 

Libavius, fuming liquor of 211 

Light, decomposition of. 49 

definition of. 48 

monochromatic. 49 

nature of 48 



Light, refraction of 48 

sources of 51 

Lignia 310 

Lime-stone 276 

Lime-water 221 

Lime 220 

hydrate of 221 

milk of. 221 

quick 2 21 

salts of. 223 

slacked 221 

sulphate of 263 

Liniment, volatile 297 

Liquefaction 34 

Liquids, expansion of 17 

conducting power of 26 

Liquorice, sugar of. 308 

Litharge 236 

Lithia 213 

Lithium 2 17 

oxide of 219 

chloride of 219 

Litmus 313 

Loadstone 230 

Logwood 313 

Lunar caustic 269 

Lupulin 317 

Lymph 333 

M. 

Madder 313 

Magnesia 223 

calcined 223,276 

Magnesium 223 

chloride of 224 

oxide of 223 

Magnetism, electro 64 

Malachite 276 

Malates 291 

Manganese 206 

chloride of 207 

fluoride of 209 

oxides of 207 

sulphuret of 209 

Manganesiate of potassa 207 

Mangauesic acid 207 

Manna. 307 

Marble 276 

Marine acid. 126 

Massicot 236 

Meconic acid 295 

Medullin 313 

Menstrum 63 

Mephitic gas 130 

Mercurial calcs 24 1 

Mercury. 240 

alloys of 243 

chloride of 242 

oxides of 241 

precipitates of, red 242 

white 242 

yellow 243 

prussiate of 243 

sulphurets of. 243 

Metallic oxides 72 

Metalloids 211 

Metals 197 

alkaline 211 

conducting power of 25 

classification of 199, 252 

electrical attraction of 64 

Metameric bodies 15S 



I X D E X 



343 



Methegliu . 308 

Meteoric stones 232 

Milk of sulphur 1S6 

sugar of. 3i>S 

Minderus, spirit of 2S8 

Mineral chamelion 207 

Minium 236 

Molybdenum 204 

chloride of 204 

oxide of. 204 

sulphuret of 204 

Mordant 312 

Morphia 294 

Mother of vinegar 287 

Mucilage 310 

Muriate of lead 237 

Muriatic acid 126 

Mushrooms, sugar of 307 

Myrica cerifera, wax from 300 

Myricin 301 

N. 

Naphtha 164 

Naphthaline 164 

Natural history 7 

Natural philosophy 7 

Narcotine 295 

Neutralization S4 

Nickel 232 

alloys of. 233 

Nicotin 3iS 

Nitrates 139, 267 

Nitrate of silver 139 

of ammonia 134,143 

Nitre 26S 

Nitric acid 138 

Nitrogen 128 

bromide of 144 

chloride of 143 

discovery of 130 

iodide of 144 

oxides of. 134 

properties of. 130 

Nitro-hydro-chloric acid 127 

Nitro-muriatic acid 127 

Nitrous acid 137 

Non metallics, division of 93 

Non metallic elements, table of 195 

Non respirable air 130 

o. 

Ochres 230 

Oil, almond 297 

castor 298 

drying 237 

linseed 297 

olive 297 

palm 298 

train 329 

varnish 297 

of turpentiue 299 

Oils, animal 329 

essential or volatile 2S6, 298 

fixed 296 

siccative 297 

Olefiant gas 163 

Olive oil 297 

Olivile 317 

Opaque bodies 4S 

Organic chemistry 71 

Orpiment 200,314 



I Ozmazome 328 

| Osmium 252 

! Oxacids 124 

| Oxalates 289 

i Oxalic acid 154, 238 

! Oxidation 95 

I Oxide, carbonic 154 

of tellurium. 205 

Oxygen 94 

combustion of 96 

discovery of. 94 

mode of obtaining 94 

properties of 75 

Oxyinel 308 

Oxymuriatic acid 100 

P. 



Palladium 251 

chlorides of. 251 

oxides of 251 

Papin's digester 43, 327 

Parilla 296 

Patent yellow 239 

Pearl white 240 

Pearlash 274 

Pectate of potassa 292 

Pectic acid 292 

Perchloric acid 105 

I Percussion powder 167 

Peruvian bark 295 

Pewter 237 

Philosopher's stone 178 

wool 233 

i Phlogiston 98, 114 

Phosphates 273 

j Phosphites 1S2 

, Phosphori solar 52 

Phosphorescence. 52 

., Phosphoret of carbon 185 

| Phosphoric acid 97, ISO 

Phosphorous acid 1S1 

Phosphorus 177 

Baldwin's 53 

Bolognian 53 

Canton's 53 

chlorides of 1S2, 1S3 

hydrate of 132 

oxideof 182 

Photometers 53 

Physical sciences 7 

Picromel 332 

Piperin 317 

Pit coal 145 

Pitch, Burgundy 299 

Plaster of Paris 263 

Platinum 243 

chlorides of 249 

fulminating 250 

oxides of 249 

spongy. 117,250 

Plumbago 146,231 

Pollenin 31S 

Polycroite 318 

Polvmeric bodies 158 

Penderables 209 

Potassa 214 

Putassium 212 

bromide of 215 

chloride of 215 

cyanuret of 215 

iodide of 215 



344 



INDEX 



Potassium, oxides of 213 

phosphuretof 215 

Precipitates 80 

Pressure, influence ou boiling point.. . 42 

Proteine 325 

Proximate principles 287, 323 

Prussian blue 282 

Prussiates 281 

Prussic acid 168, 294 

Pulse glass 39 

Putrefactive fermentation 322 

Pyroligneous acid 288 

Pyrometer 15 

Pyromucic acid 292 

Pyrophorus of Homberg 264 

Q. 

Quercitron 314 

Quick lime 221 

Quicksilver 240 

Quiuia 295 

R. 

Radiant caloric 28 

Rays, calorific 50 

chemical 50 

colorific 49 

deoxidizing 51 

Realger 200 

Rectified spirit 301 

Red dyes 313 

Refrigerator 25 

Resins 299 

Respiration 93, 135,336 

R lie unite acid 293 

Rhodium 251 

chlorides of. 251 

oxides of 251 

Rhubarbarin 317 

Rouge 313 

Rutile 202 

s. 

Saccharine fermentation 320 

Safety lamp 160 

Safflower 313 

Saffron 313 

Sago 309 

Sal ammoniac 142, 278 

Salifiable bases 72, 293 

Saleratus 274 

Saliva 333 

Salt petre 263 

Salt, definition of 71 

common 216 

spirit of 126 

of sorrel 2S9 

Glauber's 262 

Salts, acidulous 72 

classification of 261 

erystalization of. 254 

definition of 61 

deflagrating 140 

Epsom 264 

general remarks on 254 

neutral 72 

of hydracids 279 

of oxacids 262 

Seidletz 264 

sub 72 

super 72 



Sandarac 199 

Sand bath 39 

Sanguinaria 295 

Saponification 331 

Sarcocoll. 318 

Scheele's green 267 

Science, effect on the mind 8, 10 

art and 9 

Seidletz salts 264 

Selenic acid 194 

Selenious acid 194 

Selenium 194 

bromide of 194 

chloride of 194 

oxide of. 194 

phosphuret of. 195 

sulpiiuret of 195 

Separable helices 67 

Serum 333 

Siccative oils 297 

Silicates 176 

Silicon 174 

chloride of 177 

sulphate of 177 

Silicic acid 175 

Silvering 243 

Silver 214 

alloys of 245 

ammoniuret of. 245 

chloret of 245 

detonating 245 

fulminating 245 

nitrate of. 269 

oxides of 244 

Silver plate 245 

Slag 233 

Smalt 209 

Smoke 115 

Soap, glass makers 208 

portable 327 

Sod.i 2I5 

muriate of. 2 16 

Sodium 215 

alloys of 217 

chloride of 216 

oxides of 215, 216 

Solar phospliori 52 

spectrum 49 

Solder 237 

Solids, expansion of 14 

conducting power of. 24 

Solution 82, 269 

Solubility, degrees of 83 

Solvent 62 

Spar, fluor 110, 222, 279 

heavy 263 

Iceland 49 

Specific gravity 74 

caloric 33 

Spectrum, solar 49 

Spelter 233 

Spermaceti. 330 

Spliene 202 

Spirit lamp. 301 

ofsalt 126 

proof 312 

pyroxylic 305 

rectified 301 

Starch 303 

Steam 43 

elasticity of 44 



INDEX 



345 



Stearin 330 

Strontium 219 

carbonate of 220 

nitrateof •••• 220 

oxides of 219 

sulphurets of. 220 

Strychnia 295 

Suberin 317 

Sugar 305 

of grapes 307 

of lead 288 

of liquorice 308 

of milk 328 

of mushrooms 307 

of starch 307 

Sulphates 262 

Sulpho-naphthalic acid 164 

Sulpho-salts 282 

Sulphur 185 

affinity for oxygen 182 

alcohol of 192 

bromide of 192 

chloride of 192 

flowers of 186 

iodide, of 192 

milkof. 186 

Sulphurous acid 187 

Sulphuric acid 188 

ether 303 

Synovia 333 

Sympathetic ink 209 

T. 

Tannin 314, 327 

artificial 315 

Tantalum 202 

Tar 299 

Tartar-emetic 201 

vitriolated 262 

Tellurium 205 

oxides of 205 

Thermometer 20 

invention of 21 

differential, Howard's... 22 

Leslie's..-. 21 

Fahrenheit's 23 

Thermo-elecirical phenomena 68 

Thorinum 227 

carbonates of 227 

oxides of 227 

Tin « 210 

alloys of 211. 

chlorides of 211 

sulphurets of 210 

Tinfoil 210 

Tin plate 210 

Tincal 274 

Titanite 202 

Titanium 202 

oxidesof. 202 

Tourmaline 172 

Transparent bodies 48 

Trona 275 

Tungsten 205 

chloride of 206 

oxide of. 205 

Tumeric 313 

Turnsol 313 

Turpentine 299 

Type metal 201 



u. 

Ulmin 317 

Uranium 206 

oxides of. 206 

Ultimate elements 323 

V. 

Vanadium 206 

Vanadiate of lead 202 

Vaporization 36 

Vapors 46 

elasticity and condensibility of 47 

Vegetable acids 287 

albumen 317 

alkalies 293 

chemistry 286 

v , .. J ell y 3 io 

Vegetation 133 

Vegeto alkalies 72 

Veratria 296 

Verdigris . . 238 

Verditer 240, 276 

Vermilion 243 

Vinegar 287 

Vinous fermentation 320 

Vital air 94 

Vitality 334 

Verifiable earth 176 

Vitriolated tartar 262 

Vitriol, blue 266 

green 229 

white 234, 266 

Volatile liniment 297 

Volta 55 

Volta's electro induction 66 

Voltaic pile 56 

currents 65 

Volumic theory , 91 

w. 

Water, analysis of 120 

carbonated 151 

decomposition of 61, 1 15 

of crystalization 122 

of interposition 26S 

of nitre 140 

Wax 300 

Whey . . , 328 

White lead 276 

Woody fibre 310 

Wolfram 206 

Y. 

Yeast 316 

Yellow dyes 313 

patent 239 

Yttrium 227 

z. 

Zaffire 209 

Zimome 316 

Zinc blende 233 

Zinc 233 

chloride of 234 

flowers of 233 

muriate of. 234 

oxide of. 234 

Zirconium • 226 

oxide of 226 






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